HK2 and breast cancer: Circular RNA (circRNA) can specifically adsorb miRNA, and CircRNA microarray sequencing has shown that miR-487a carried by CircRNF20 in breast cancer can promote the binding of HIF-1α to the HK2 promoter, thereby enhancing the transcription and expression of HK2 and promoting the proliferation of breast cancer cells through the Warburg effect [91].