For example, hypoxia-activated chk1 inhibitors were recently developed as proof-of-principle molecules for targeting the hypoxic compartment of tumours, where chk1 is an important component of the DNA damage response and cell cycle progression.261 From these studies, it is clear that the emerging application of microenvironmental-targeted agents in combination therapies can improve patient outcomes, and as newer generation inhibitors are developed, we are likely to see a wider application of these agents entering the clinic. Here, CHEK1 is linked to neoplasm.