E2F1 and cancer: Meiotic nuclear divisions 1 (MND1) may competitively bind to KLF6, protecting E2F1 from KLF6-induced transcriptional repression and forming a positive feedback loop in the MND1-KLF6/E2F1 axis, thereby downregulating the inhibitory effect of KLF6 on cancer cells, which promotes cell cycle progression in cancer tissues (132).