CDKN2A and lung cancer: RT-qPCR analysis of ARF expression demonstrated a significant increase in ARF mRNA levels in SIRT7-depleted H1299 cells but not in Calu-3 cells (SI Appendix, Fig. S1H), indicating that SIRT7 not only influences ARF stability but also interferes with gene expression or mRNA stabilization at least in some lung cancer cells.