SKP2 and prostate cancer: In prostate cancer cell lines PC3 and LNCaP, the IC50 values of Skp2 inhibitor SZL-P1-41 (i.e., #25) was 5.61 μM and 1.22 μM respectively (Chan et al., 2013), much lower than the natural Skp2-inhibiting compounds Gartanin (13.56 μM, 8.32 μM) (Pham et al., 2020) and Safranal (0.512 mM, 0.234 mM)(Jiang et al., 2020), and also lower than SMIP004(40 μM in LNCaP)(Rico-Bautista et al., 2010), a non-structure-based compounds.