TP53 and cancer: Beyond TCGA molecular subtypes, the Asian Cancer Research Group (ACRG) has also categorized gastroesophageal cancers, and proposed four subtypes based solely on gene expression signatures: MSI, MSS/epithelial‐to‐mesenchymal transition (EMT), MSS/TP53‐active, and MSS/TP53‐deficient tumors.49