TP53 and non-small cell lung carcinoma: Recent RNA sequencing efforts in KRAS+ NSCLC defined three expression clusters dominated by the co-mutations in serine/threonine kinase 11 (STK11, also known as liver kinase B1 (LKB1)) and tumor protein p53 (p53), inactivation of cyclin-dependent kinase inhibitor 2A/B (CDKN2A/B) and low levels of thyroid transcription factor-1 [21].