It is known that when PERK is phosphorylated UPR becomes activated. I induced toxicity in BM-MSC cells to activate the UPR. However, when I performed western blotting, I could not visualize the p-PERK. I completed 48 hours of primer incubation, and in an another experiment I completed a 1:500 dilution of primer antibody for 24 hours but I couldn't detect etc. Do you have any suggestions for me to obtain p-perk western blot? Also CHOP and ATF4. I have similar issues with these proteins.