AP-1 elements are involved in PTPROt transcription and are essential for its transcription. U937 cells treated with 10 ng/mL TPA for 24 hours were used for expression of PTPROt, c-fos, and c-jun by real-time RT-PCR (A) and expression of c-fos and c-jun by Western blot (B). Error bars represent SD. P values were calculated using the Student t test. (C) Formaldehyde cross-linked chromatin from control and TPA-treated (10 ng/mL) U937 cells was used for immunoprecipitation with antibodies specific for c-fos and c-jun followed by PCR for PTPROt promoter. The data are normalized to input and represented as fold enrichment in TPA-treated cells over control cells. The experiment was repeated twice with similar results. Error bars represent SD. Depletion of c-jun in U937 cells by siRNA was measured by real-time RT-PCR (D) and Western blot (E). (F) Effect of c-jun siRNA on basal and TPA-induced expression of PTPROt was assessed by real-time RT-PCR. The experiment was repeated twice with similar observations. Error bars represent SD. P values were calculated using the Student t test.