siRNA of PERK, IRE1 and ATF6 was co-transfected into Jurkat cells to knockdown the proteins. Expression of PERK, IRE1, ATF6, and cleaved PARP was determined by Western blot. Total pixels of each protein band were used for graphing and statistic analysis, based on at least three independent Western blot experiment results (A). Cell proliferation in the vehicle and transfected cells was analyzed as described in the Materials and Methods section (B). Vehicle, transfection reagent only; siRNA mixtures, siRNA mixtures of PERK, IRE1, and ATF6. IRE1, inositol-requiring protein-1; ATF6, activating transcription factor -6; PERK, protein kinase RNA-like ER kinase; PARP, poly ADP ribose polymerase. *, p ≤ 0.05.