Fig. 2

Reciprocal feedback loops between HIF-1α and ncRNAs. In addition to a unidirectional regulation pattern, there are several direct or indirect feedback loops between HIF-1α and ncRNAs. It seems quite feasible that the ncRNAs, HIF-1α and other co-operators would eventually intertwine to form mutually reciprocal feedback loops in both positive and negative manners. In addition to common feedback loops, lincRNA-p21 and HISLA can block VHL- and PHD-dependent HIF-1α repression instead of directly interacting with HIF-1α and other co-operators.