NRF1 and colorectal carcinoma: Multiple mechanisms regulating CXCR4 expression in CRC are likely involved, including DNA epigenetic processes such as increases in 5hmC in the CXCR4 gene body [52], acquisition of activating and loss of repressive histone marks such as increased H3K4me3 and decreased H3K27me3, respectively, [77]; and recruitment of trans-activating factors such as nuclear respiratory factor1 (NRF1) [78].