CtBP1 co-localized with KLF4 on the promoters of KLF4 downstream target genes. A. AGS cells were transfected by pMyc-KLF4, pFLAG-CtBP1, and the respective vectors. CHIP assays were performed to examine the occupancy of KLF4 and CtBP1 on the promoters of KLF4 downstream target genes, including IAP, KRT4, p21, CCND1, HDC and LAMA1. (B). pMyc-KLF4, pFLAG-CtBP1 KLF4, and the respective vectors with different combinations were transfected into KLF4 null MEFs for CHIP assays. Occupancy of CtBP1 on the promoters of IAP, KRT4, p21, CCND1, and HDC were examined to test the dependence of KLF4.