- The gene (PTPN13) encoding the protein tyrosine phosphatase PTP-BL/PTP-BAS is located in mouse chromosome region 5E/F and human chromosome region 4q21. van den Maagdenberg, A.M., Olde Weghuis, D., Rijss, J., Merkx, G.F., Wieringa, B., Geurts van Kessel, A., Hendriks, W.J. Cytogenet. Cell Genet. (1996)