Feature	Nuclease Protection Assays	Northern Blotting	RT-PCR	In Situ Hybridization
Relative and Absolute Quantitation	Yes	Yes	Yes	Yes
Detection Limit (Copies of mRNA)	4,000-5,000	10,000	1 (theoretical)	Medium
Level of Optimization Required	Medium	Medium	High	High
Sample Size	100 µg max	30 µg max	Not critical	Tissue sections
Detect Multiple Transcripts	Yes, in same tube	Yes, generally requires stripping and reprobing	Yes, in same tube	No
Localizes mRNA Expression within Tissues/Cells	No	No	No	Yes
Mapping Studies	Yes	No	No	No
Resolve Comigrating mRNAs	Yes	No	Yes	No
Sizing mRNAs	No	Yes	No	No
Detection of Alternatively Spliced Transcripts	No	Yes	No	No
Distinguish Between Members of Multi-Gene Families	Yes	Only if they are different sizes	Only if they are characterized	No
Tolerates Partially Degraded RNA	Yes	No	Yes	Yes
Advantages	Can use up to 100 µg of sample RNA Ease of multiprobing Tolerates partially degraded RNA	RNA undergoes minimal processing Technique can be easily evaluated at various points in procedure	Most sensitive technique available	Localized mRNA within tissue Tolerates partially degraded RNA