CDK6 and esophageal squamous cell carcinoma: However, instead of ERBB2 and VEGFA amplifications that are frequently observed in EAC [16], this case had oncogenic [27] amplifications of CCND1, FGF19, PIK3CA, BCL6, TERT, PIK3CB, CDK6, and GAB2, almost all of which (all except CDK6) are much more frequently observed in ESCC than EAC (Figure 7D).