Roscovitine demonstrates broad-spectrum anticancer activity via multiple mechanisms: inhibition of estrogen receptor-α phosphorylation in hormone-responsive breast cancer (91), cdk5-mediated regulation of invasive breast cancer proliferation (92), chemosensitization of colorectal cancer cells to conventional cytotoxic agents (93), and central analgesic effects through modulation of NMDA receptor 2B subunit expression (94). This evidence concerns the gene ESR1 and breast cancer.