TP53 and lung adenocarcinoma: Interestingly, while loss of menin increases γH2AX positivity in lung adenocarcinoma cells, consistent with downregulation of p53, it also increases activating phosphorylation of ATM, and the expression of the homologous recombination (HR) protein RAD51 and the non-homologous end joining (NHEJ) proteins Ku70/Ku80 [108].