STAT5A regulates SOCS2 expression in HNSCC cells. (A) TU167 and Osc19 cells were transfected with nontargeting scrambled siRNA or STAT5A- or STAT5B-specific siRNA either alone or in combination (KD, knockdown). Cells were harvested and lysed after 72 hours of transfection, and the indicated molecules were visualized using Western blot analysis. SOCS1 and SOCS2 expression was normalized with that of β-actin (bar graph). (B) TU167 cells were transfected with STAT3-specific siRNA and analyzed by Western blot analysis 72 hours later. (C) TU167 and Osc19 cells were transiently transfected with empty vector, CA-STAT5A or CA-STAT5B (OE, overexpression), or both. Cells were harvested and lysed after 72 hours of transfection, and the indicated molecules were visualized using Western blot analysis. The terms lighter and darker refer to film exposure. SOCS1 and SOCS2 expression was normalized with that of β-actin (bar graph).