POLR2A and cancer: Interestingly, among several well‐established CRL5 substrates that were examined, including integrin β1, p‐SRC (Y416), ATM, RPB1, EGFR, DEPTOR, and NOXA,[16] only integrin β1 consistently accumulated across all cancer cell lines upon APC11 knockdown using two independent siRNAs targeting APC11 (Figure 3a).