Stable T-plastin surexpression in Jurkat cells induces apoptosis resistance to etoposide and T-plastin down-regulation by siRNA partially restored apoptosis. (A) Cytoplasmic expression and whole protein expression of T-plastin by mmunostaining (top panel) and Western blotting (bottom panel), respectively, for 1 representative T-plastin–transfected clone (Jurkat pcDNA3.1/PLS3) and 1 sham-transfected clone (Jurkat pcDNA3.1). Immunoblots from wild-type, nontransfected Jurkat cells (WT) are shown in the first column of the bottom panel. The immunoblot membrane was stripped and reprobed for expression of β-actin to control for loading (bottom panel). (B) Stable T-plastin–expressing Jurkat clones (pcDNA3.1/PL3) and vector control Jurkat clone (pcDNA3.1) were exposed to etoposide (2 or 5 μM) or not (Basal) for 24 hours. Apoptosis was determined as in Figure 3A. Top panel: data are presented for 1 representative pcDNA3.1 clone and 1 pcDNA3.1/PLS3 clone. Bottom panel: results are mean relative percentages (± SEM) of etoposide-induced apoptosis from pcDNA3.1 (white) and pcDNA3.1/PLS3 (gray) clones relative to apoptosis of respective clones, nonexposed to etoposide (Basal) and taken as 1 (n = 12). *P < .05, **P < .01, comparison of apoptosis of pcDNA3.1/PLS3 clones with that of pcDNA3.1 clones incubated with the same respective concentration of etoposide.