Expression of siRNA to RAX promotes cell survival in medium with low serum. (A) Western blots using cell lysates from MEFs expressing the indicated siRNAs as well as from cell lines that express exogenous RAX or RAX(S18A). (B) Growth rate of MEF cell lines under serum-replete (10%) conditions. (C) Viability measured by TUNEL assay in medium with low (0.1%) serum of cell lines with reduced RAX levels caused by siRNA expression or expressing either exogenous RAX or RAX(S18A).