FIG. 6.

Immune complex phosphatase assays. Cos-1 cells were transfected for 18 h with cDNAs coding for N-Myc-PTP1B, N-Myc-PTP1B-D24A, N-Myc-PTPLB, and N-Myc-PTPLB-P101R. The protein expression levels were monitored by immunoblotting of the anti-Myc immunoprecipitates with anti-Myc antibodies, and the abundances of the proteins were adjusted to the same levels. The PTPase activity assay was performed as described in Materials and Methods. The absorbance at 410 nM represents the quantities of the dephosphorylated product of pNPP.