The ERCC ExFold RNA Spike-In Mixes provide a set of external RNA controls that enable performance assessment of a variety of technology platforms used for gene expression experiments. Add one Spike-In Mix to each RNA sample, and run the Spike-In Mix-containing samples on your platform. Then compare the Spike-In Mix data to known Spike-In Mix concentrations and ratios to assess the dynamic range, lower limit of detection, and fold-change response of your platform. A number of gene expression technologies can benefit from the use of the ERCC ExFold RNA Spike-In Mixes, including next-generation sequencing (NGS), microarrays, and PCR-based assays. Microarrays must contain probes designed to interrogate the ERCC transcripts to benefit from the use of the ERCC ExFold RNA Spike-In Mixes. Consult with the array manufacturer for details. Key product features:

• Achieve a standard measure for data comparison across gene expression experiments
• Measure sensitivity (lower limit of detection) and dynamic range of an experiment
• Quantitate differential gene expression

Why external RNA controls are needed
Variation in RNA expression data can be attributed to a variety of factors including the quality of the starting material, the level of cellularity and RNA yield, the platform employed, and the person performing the experiment. To control for these sources of variability, a common set of external RNA controls has been developed by the External RNA Controls Consortium (ERCC), an ad-hoc group of academic, private, and public organizations hosted by the National Institute of Standards and Technology (NIST). The controls consist of a set of unlabeled, polyadenylated transcripts designed to be added to an RNA analysis experiment after sample isolation, in order to measure against defined performance criteria. Up until the design of such universally accepted controls, it has been difficult to execute a thorough investigation of fundamental analytical performance metrics. From the trusted brand of quality RNA reagents, ERCC ExFold Spike-In Mixes are commercially available, pre-formulated blends of 92 transcripts, derived and traceable from NIST-certified DNA plasmids. The transcripts are designed to be 250 to 2,000 nt in length, which mimic natural eukaryotic mRNAs.

Unlock the potential of RNA analysis
RNA analysis, including gene expression profiling and whole transcriptome surveying, can lead to better understanding of expression patterns in disease states and provides greater insights into biological pathways and molecular mechanisms that regulate cell fate, development, and disease progression. Traditional methods of RNA analysis, such as qRT-PCR and microarrays, are well established but are being replaced by next-generation sequencing, a high-throughput digital alternative. Because each method carries multiple platforms, and with the need to compare various samples across platforms throughout the world, a standard measure for data comparison is necessary. As the capabilities of RNA analysis expand, the necessity to create a standardized view of data will become even more important.

Achieve and compare results with confirmed accuracy
ERCC ExFold RNA Spike-In Mixes are used to create a standard baseline measurement of RNA both within an experiment and across multiple experiments performed using various samples and platforms. With two spike-in mix formulations (see figure), various measurements, such as sensitivity or dynamic range, can be examined to assess different parameters in an experiment or across experiments (see figure). Furthermore, expression fold-change ratios between two samples can be calculated with a high degree of confidence using the highly concordant relationship between ExFold RNA Spike-In 1 and ExFold RNA Spike-In 2 (see figure). Measurements are determined via known molar concentrations for each transcript within a spike-in mix and through association of the two mixes using a combination of ratios across 4 different subgroups of the 92 transcripts. The controls are ideal for next generation sequencing experiments, such as on SOLiD™ System, and supported microarray platforms such as the Illumina™ Sentrix™ BeadChip.

Choose among flexible options for ERCC kit configurations
Whether measuring dynamic range or gene expression fold-change, ERCC Spike-In Control Mixes are available in two kit configurations to meet your experimental needs. Use the ERCC Spike-In Mix to determine the dynamic range and lower limit of detection on your platform, and use the ERCC ExFold Spike-In Mixes to assess the accuracy of differential gene expression measurements.

	ERCC RNA Spike-In Mix 1*	ExFold Spike-In Mix 1*	ExFold Spike-In Mix 2*	Nuclease-free Water
ERCC RNA Spike-In Mix (Cat. No. 4456740)	10 µL	—	—	1.75 mL
ERCC ExFold RNA Spike-In Mixes (Cat. No. 4456739)	—	10 µL	10 µL	1.75 mL

* Although ERCC RNA Spike-In Mix 1 and ExFold Spike-In Mix 1 contain the same formulation of ERCC transcripts, do not substitute ERCC RNA Spike-In Mix 1 for ExFold Spike-In Mix 1 for fold-change assessment. Use only ExFold Spike-In Mix 1 and Mix 2 with the same manufacturing lot number.