PTPN1 KO and PTPN2 KO cells show increased phosphorylation of SHP2, STAT3 and ERK compared with WT cells following crizotinib treatment. (A-B) Western blot analysis of PTPN1 KO or PTPN2 KO TS cells treated with the indicated concentrations of crizotinib for 4 hours. Cell lysates were blotted with the indicated antibodies. β-actin was used as a loading control. One representative experiment of 3 with comparable results is shown. (C) Western blot analysis performed on JB6 cells transduced with a doxycycline-inducible lentivirus expressing PTPN1 or PTPN2. Cells were induced with doxycycline for 24 or 48 hours and collected. Cell lysates were blotted with indicated antibodies. β-actin was used as a loading control. (D) Quantification of PTPN1, PTPN2, pALK (Tyr1604), and pALK (Tyr1278) expression levels following PTPN1 or PTPN2 overexpression induced by doxycycline in JB6 as in panel C. Data are represented as means ± SD of average of the 24- and 48-hour time points. The P value was determined by multiple t tests.