TP53 and malignant colon neoplasm: CRISPR/Cas9 was used to insert a ~600 bp blasticidin gene and poly A site into exon 4 (amino acid 40) of ORC2 in HCT116 p53-/- (Bunz et al., 1998) colon cancer cells (WT: HCT116 p53-/-, ORC2+/+) (Figure 1A and B).