We have found that the ablation of Chk1, a serine-threonine kinase that is activated after DNA damage, strongly reduced the formation of chemically (DMBA/TPA) induced skin tumours, thus suggesting a role of this protein in hair follicle stem cells population, from which tumours are thought to arise. We have observed that deletion of Chk1 causes cell proliferation, DNA damage, and apoptosis within ...