TP53 and neoplasm: It is worth noting that while s.c. xenograft tumors formed by p53−/− RKO cells grew much faster than tumors formed by p53+/+ RKO cells, which indicates the tumor-suppressive function of wtp53, TRIM21 knockdown displayed a much less pronounced growth-promoting effect on p53+/+ RKO tumors compared with its effect on the above-mentioned mutp53 tumors (Supplemental Figure 4D).