Hypoxia-induced increases in tumor cell coagulability are HIF1-dependent. Wild-type (WT) and HIF1α knockout (HIF1ko) LLCs and MECs were cultured under ambient (21%) and hypoxic (1%) oxygen conditions, after which (A-B) cell adhesion to fibrin, (C-D) cell coagulation times, and (E-F) fibrin deposition were assessed (n = 5 per group). *P < .05 and **P < .01.