By contrast, knockout of CDH1 largely blocked PIN1 inhibitor- and CDK4 inhibitor-induced activation of APC/CCDH1, evident from the increased levels of mitotic proteins, but not mRNA levels, in both RB-proficient and RB-deficient BC cell lines (Fig. 5g, h, Supplementary Fig. 7e–j), supporting the direct role of PIN1 and CDK4 in the regulation of APC/CCDH1. Here, PIN1 is linked to breast cancer.