FAT4 and acinar cell carcinoma: In the 17 acinar cell carcinomas, 4 tumors harbored somatic mutations in SMAD4; 3 in JAK1, RB1, and TP53; 2 in APC, ARID1A, GNAS, MLL3, PTEN, FAT4, and CTNNB1; and 1 in BRAF, ATM, BAP1, BRCA2, PALB2, RNF43, FAT2, TSC2, and MSH2. Some of the protein products of these mutated genes are druggable, which may pave the way for the development of specific drugs for acinar cell carcinoma.