Elevated expressions of stress-related proteins in SMN-deficient ES cells. Control (C) and SMA (S) ES cells as described in 3A were processed for western blotting using antibodies against phosphorylated p38 (pP38), p38, phosphorylated JNK (p-JNK), JNK, and TIA-1. The same membranes were stripped and re-probed with anti-ERK antibody for protein loading control (A). Signals of three independent experiments were quantified, normalized to corresponding ERK signals, and plotted as for 3B. SMA ES cells express significantly higher levels of phosphorylated p38, phosphorylated JNK, and TIA-1 proteins (** p < 0.01 and * p < 0.05) (B). Undiff. = undifferentiated cells and Diff. = differentiated cells.