ERBB2 and neoplasm: A splice variant of full-length HER2 mRNA and a collection of HER2 truncated carboxy-terminal fragments, known as d16HER2 and p95HER2, respectively, have been characterized as the most oncogenic HER2 isoforms with significant implications in the regulation of HER2+ breast CSC features, including tumor initiation, EMT induction, and resistance to targeted therapy [284].