MAPKs are involved in IL-1β-induced PCSK9 secretion. (A) and (B) IL-1β and PCSK9 secretion and MAPKs expression. (C) and (D) PCSK9 expression in WT mice, ERK-/-, JNK-/- and P38-/- mice. (E) ELISA analysis for PCSK9 secretion in MPM culture medium. ****P<0.0001 vs. WT control. (F) to (H) PCSK9 expression in different tissues from ERK-/-, JNK-/- and P38-/- mice measured by western blot or immunofluorescent staining. Scale bar: 20 µm. (I) Serum mPCSK9 levels in WT, ERK-/-, JNK-/- and P38-/- mice. ****P<0.0001 vs. WT + saline; ++P<0.01, ++P<0.001 vs. WT. Western blots in each group were performed with the same protein concentration and the same film exposure time. Data represent the mean ± SD of independent experiments (n=5 mice per genotype in cell experiments and n=7 mice per genotype in animal experiments), each performed in triplicate. MPMs: mouse peritoneal macrophages.