PIN1 and cancer: Pin1 is a phosphorylation-dependent enzymethat catalyzes the cis–transisomerization of prolyl amide bonds,1−4 playing an important role in regulatingthe cell cycle,1,5 and many diseases, including cancer,Alzheimer’s, immune disorders, and infections.6−8 Pin1 contains two domains, the catalytic peptidyl-prolyl isomerase(PPIase) domain and WW (Trp-Trp) domain.9−11 The Pin1 WW domain andthe PPIase domain both recognize and bind the pSer/pThr–Promotif.2,9,10 Pin1 interactswith a large number of cell cycle and transcriptional regulatory proteinsvia both PPIase and WW domains.2,9,12−14