ER targeting partially restores the NFAT activation mediated by mutant p12I 15-47. (A) Localization of mutant 15-47 and chimeric protein 15-47KKLL. An ER targeting signal, KKLL, redirected the chimeric protein 15-47KKLL to ER compartments stained with the ER marker, calreticulin (CRT). The nuclei were stained with Hoechst stain. (B) Relative NFAT activities mediated by p12I, mutant 15-47, and chimeric protein 15-47KKLL. Data are presented as relative NFAT luciferase activities compared to wild-type p12I. Values are means of three independent transfection experiments. Statistical significance was analyzed by using the Student t test. ✽, P < 0.05.