RB1 and colon adenocarcinoma: This reciprocal relationship was less evident in tumors that rarely exhibit RB1 loss (e.g., colon cancer-COAD) or tumors where the RB-pathway is inactivated in veritably all tumors by the presence of HPV (e.g., cervical cancer-CESC) that yields RB inactivation via the E7 viral oncoprotein29 (Fig. 1f).