HIF1A and breast cancer: Moreover, circRNF20 (hsa_circ_0087784), circulated from RNF20 gene exon-3 to exon-5, has been newly identified in breast cancer samples, and promotes the progress and glycolysis of breast cancer by abrogating the miR-487a-mediatied inhibition of the HIF-1α/HK2 axis [38].