CHEK1 and melanoma: Since checkpoint kinase 1 (Chk1) plays a pivotal role in controlling cell cycle progression, Hwang et al. reported that PF477736 (a potent and specific inhibitor of Chk1) effectively promotes Vem-resistant melanoma cells to regain sensitivity to Vem by lowering the total level of Chk1 and modifying its phosphorylation (Hwang et al., 2018).