Fig. 4.

Activation of p38 signaling pathways in response to hypoosmotic stress. Western blotting analyses of human erythrocyte membranes following erythrocyte incubations in pink test buffer (2 h) in the presence or absence of p38 MAPK inhibitors SCIO469 (50 μmol/L) or SB203580 (50 μmol/L). A. Representative immunoblots of phosphorylated (p-) and total MKK3, p38 MAPK, MAPKAPK2, RSK2, and actin. Quantified protein expressions (normalized to actin) are shown in B–I. B. Phospho-MKK3; *p < 0.05. C. Total MKK3; *p = 0.048. D. Phospho-p38 MAPK; **p < 0.005. E. Total p38 MAPK; ***p = 0.0005. F. Phospho-MAPKAPK2 (p-MK2). G. Total MAPKAPK2 (MK2). H. Phospho-RSK2; *p = 0.0313, **p = 0.0072. I. Total RSK2; p = 0.0157. B–G: N = 6 for SCIO469 and N = 4 for SB203580 treatments. H–I: N = 6. All p values were obtained by mixed-effects ANOVA analysis and Fisher’s LSD test, except for panel E, where Kruskal–Wallis test was used. Data were collected from 4 independent experiments and are presented as box and whiskers (median and min to max). In all analyses, the mean effect of each inhibitor or untreated controls was compared to hypoosmotic treatment.