PARP1 and non-small cell lung carcinoma: ATP is required to enhance the activity of receptor tyrosine kinases such as EGFR, which are in turn involved in signaling pathways needed for the survival and growth of NSCLC cells, while NAD+ is a substrate for enzymes such as poly (ADP-ribose) polymerase-1 and sirtuin that contribute to apoptosis resistance and tumor cell survival [16].