Hypoxia-induced decreases in the clotting times of tumor cell–conditioned media are dependent on HIF1α and TF/FVII. Wild-type (WT) and HIF1α knockout (HIF1ko) LLCs and MECs were cultured under ambient (21%) and hypoxic (1%) oxygen conditions, after which (A-B) conditioned media (CM) coagulation times were assessed (n = 5 per group). Clotting times were also assessed in WT LLC- and MEC-conditioned media (n = 5 per group) with (Anti-) or without (Vehicle IgG) inhibition of TF (C-D) or FVII (E-F), and with (Control) or without (Sedimented) the presence of secreted microvesicles (G-H). *P < .05, **P < .01, ***P < .001.