ERBB2 and squamous cell carcinoma: This was further validated in the context of the tumor molecular subtype via the Lund taxonomy classification system, which demonstrated ERBB2 amplification in the genomic unstable (GU) subtype, also considered the luminal subtype, of UC [20], and absent ERBB2/ERBB3 expression in the basal/squamous cell carcinoma (SCC)-like subtype [21].