WEE1 and cancer: Secondly, and importantly for cancer therapy, the upregulation of Cdk1 activity by Wee1 inhibition can force cancer cells to enter mitosis with under-replicated or unrepaired chromosomes leading to mitotic catastrophe and chromosome fragmentation (Figures 6A, B) (Aarts et al., 2012; Duda et al., 2016; Lewis et al., 2017).