Immunofluorescence analysis of HPK1 was performed using 70% confluent log phase Jurkat cells. The cells were fixed with 4% paraformaldehyde for 10 minutes, permeabilized with 0.1% Triton™ X-100 for 10 minutes, and blocked with 1% BSA for 1 hour at room temperature. The cells were labeled with HPK1 (2A1) Mouse Monoclonal Antibody (Product # LFMA0211) at 1:250 dilution in0.1% BSA and incubated for 3 hours at room temperature and then labeled with Goat anti-Mouse IgG (H+L) Superclonal™ Secondary Antibody, Alexa Fluor® 488 conjugate (Product # A28175) at a dilution of 1:2000 for 45 minutes at room temperature (Panel a: green). Nuclei (Panel b: blue) were stained with SlowFade® Gold Antifade Mountant with DAPI (Product # S36938). F-actin (Panel c: red) was stained with Rhodamine Phalloidin (Product # R415, 1:300). Panel d represents the merged image showing cytoplasmic and membranous localization. Panel e shows the control without primary antibody. The images were captured at 60X magnification.
|Tested species reactivity||Human|
|Host / Isotype||Mouse / IgG1, lambda|
|Immunogen||Recombinant human protein purified from E.coli(His/ABD-HPK1)|
|Storage buffer||HEPES with 0.15M NaCl, 0.01% BSA, 50% glycerol|
|Contains||0.03% sodium azide|
|Storage Conditions||-20° C, Avoid Freeze/Thaw Cycles|
|Tested Applications||Dilution *|
|Flow Cytometry (Flow)||1:20|
|Immunoprecipitation (IP)||3 µl|
|Western Blot (WB)||1:5000|
* Suggested working dilutions are given as a guide only. It is recommended that the user titrate the product for use in their own experiment using appropriate negative and positive controls.
A suggested positive control for this product is Jurkat T cells.
The c-Jun amino-terminal kinases (JNKs)/stress-activated protein kinases (SAPKs) play a crucial role in stress responses in mammalian cells. The mechanism underlying this pathway in the hematopoietic system is unclear, but it is a key in understanding the molecular basis of blood cell differentiation. We have cloned a novel protein kinase, termed hematopoietic progenitor kinase 1 (HPK1), that is expressed predominantly in hematopoietic cells, including early progenitor cells. HPK1 is related distantly to the p21(Cdc42/Rac1)-activated kinase (PAK) and yeast STE20 implicated in the mitogen-activated protein kinase (MAPK) cascade. Expression of HPK1 activates JNK1 specifically, and it elevates strongly AP-1-mediated transcriptional activity in vivo. HPK1 binds and phosphorylates MEKK1 directly, whereas JNK1 activation by HPK1 is inhibited by a dominant-negative MEKK1 or MKK4/SEK mutant. Interestingly, unlike PAK65, HPK1 does not contain the small GTPase Rac1/Cdc42-binding domain and does not bind to either Rac1 or Cdc42, suggesting that HPK1. activation is Rac1/Cdc42-independent. These results indicate that HPK1 is a novel functional activator of the JNK/SAPK signaling pathway.
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