Irreversible PIN1 inhibitor (S)-2 (IC50 = 3.2 μM), and its derivatives recently designed by Ieda et al. show the inhibition of Pin1 in protease-coupled in vitro assay and the reduction of cyclin D1 expression in PC-3 prostate cancer cell (Ieda et al., 2019). The gene discussed is PIN1; the disease is prostate carcinoma.