In order to generate AP4-deficient colorectal cancer cell lines, DLD-1 and SW480 cells were transfected with pSp-Cas9-GFP vectors expressing three guide RNAs targeting exon 2 of the TFAP4/AP4 gene, which encodes the DNA binding region of AP4 (Fig. 1A). This evidence concerns the gene TFAP4 and colorectal cancer.