Recently, Liu et al. identified perfluorodecanoic acid (PFDA), a common persistent environmental pollutant, as a XRCC4 inhibitor which was able to sensitize gastric cancer cells to chemotherapy; however, mechanism of action, target engagement with XRCC4 and the toxicity profile of the inhibitor needed to be explored in more details (117). The gene discussed is XRCC4; the disease is gastric cancer.