Characterization of PTP1B expression in cHL cell lines. (A) Western blot analysis of the indicated cHL cell lines and a lymphoblastoid cell line (LCL), using PTP1B and β-actin specific antibodies. (B) Quantification of the amount of PTP1B protein as depicted in A. Mean value of 3 independent experiments is shown, and significance was determined by a Student t test in comparison with the LCL values. *P ≤ .05; **P ≤ .01; ***P ≤ .001. (C) Immunocytochemical staining of PTP1B in the cHL cell lines L-428, SUP-HD1, and U-HO1. Original magnification ×400. (D) Endpoint PCR results of the amplified PTP1B cDNA of the cell lines L-428, U-HO1, and SUP-HD1. PCR products corresponding to the PTPN1 cDNAs of different size are marked by arrows.