FAT1 and metastatic neoplasm: FAT1 was found to harbor nonsense mutations in 40–45% of both sporadic and aggressive cases of cSCC, leading to its inactivation [27,28], while another study that concentrated on the differential expression between primary and metastatic tumors found an increased rate of FAT1 mutation in primary tumor samples (37%), in comparison to metastatic cSCC (22%) [30].