Similarly as observed in skin in vivo in benign nevi, the precursor lesion to melanoma [23], BRAFV600E lung tumors failed to progress to carcinoma, and instead, exhibited growth arrest and senescence-like features that could be overcome through concurring mutation of tumor suppressors p53 or p16Ink4a/p19ARF, allowing tumors to progress to carcinomas [7]. The gene discussed is TP53; the disease is melanoma.