After treatment with bakuchiol, the expression levels of P-Cdc2 (Tyr15), Myt1 and P-Wee1 (Ser642) were upregulated in breast cancer cells, thus suggesting that bakuchiol-induced Cdc2 (Tyr15) phosphorylation may play a central role in S phase arrest in bakuchiol-treated cells. This evidence concerns the gene WEE1 and breast cancer.