EPAS1 and cancer: Although the results of those studies implicate HTATIP2 as a HIF2α target gene involved in cancer progression and chemoresistance, questions remain about whether HTATIP2 is related to another key modulator of cellular response to hypoxia stress, HIF1α, and whether repression of HTATIP2 contributes to tumor progression by fine-tuning the balance between HIF1α and HIF2α given the fact that HIF1α and HIF2α have distinct but complementary roles in hypoxic adaptation and exhibit antagonistic activities at times [33].