COMMD4 and non-small cell lung carcinoma: To confirm our flow cytometry data, we measured the cleavage of poly (ADP-ribose) polymerase (PARP) by immunoblotting, a hallmark of apoptosis.40 This demonstrated that COMMD4 depletion by siRNA resulted in PARP cleavage in NSCLC cells, indicating the induction of apoptosis.