TP53 and lung adenocarcinoma: The inhibitor of apoptosis-stimulating protein of p53 (iASPP) protein, encoded by the protein phosphatase 1 regulatory subunit 13-like (PPP1R13L) gene, is a key inhibitor of the p53 pathway and promotes carcinogenesis in various tumors, but its role in brain metastasis of lung adenocarcinoma is unknown.