We had previously observed that NU6102 inhibited CDK1-dependent nucleolin phosphorylation and CDK2-dependent pRb phosphorylation with equal efficiency in MCF7 cells (Davies et al, 2002), and other studies show that 8 μM NU6102 inhibited CDK1-dependent phosphorylation in prostate cancer cells (Chen et al, 2006). Here, RB1 is linked to prostate cancer.