Dephosphorylates a range of proteins, and thereby regulates cellular signaling cascades (PubMed:18559503). Dephosphorylates cellular tyrosine kinases, such as ERBB2 and PTK2B/PYK2, and thereby regulates signaling via ERBB2 and PTK2B/PYK2 (PubMed:17329398, PubMed:27134172). Selectively dephosphorylates ERBB2 phosphorylated at 'Tyr-1112', 'Tyr-1196', and/or 'Tyr-1248' (PubMed:27134172). {ECO:0000269|PubMed:17329398, ECO:0000269|PubMed:18559503, ECO:0000269|PubMed:27134172}. This is the function of Ensembl gene identifier ENSG00000127947 (PTPN12, protein tyrosine phosphatase non-receptor type 12).