BCL2L1 and breast cancer: Additionally, we have reported that YY1 is capable of regulating KLF4 [59], while in KLF4/KLF5 deficient mammary cancer cells, the expression of Mcl1 and BCL-xL are reduced, suggesting a possible participation of KLF4 in the regulation of the protein [82] which is consistent with our analysis of potential binding sites for KLF4 in the BCL-xL promoter (Table 1).