A series of molecular signals initiated by binding of a ligand to a member of the ERBB family of receptors on the surface of a cell, where the signal is transmitted by ERBB2. The pathway ends with regulation of a downstream cellular process, e.g. transcription. ERBB2 receptors are themselves unable to bind to ligands, but act as a signal-amplifying tyrosine kinase within a heterodimeric pair. (Gene Ontology, GO_0038128)
