SERPINE1 and neoplasm: Besides CA-IX, the activation of the HIF-1 transcriptional complex promotes the expression of plasminogen activator inhibitor-1 (PAI-1), a member of the superfamily of serine-protease inhibitors (or serpins), which, according to the literature, has a paradoxical pro-tumorigenic role in cancer, promoting tumor cell survival and angiogenesis [153].