Fig 1: PCA negatively regulates the osteoclastogenesis-associated MAPK and Akt signaling pathways and critical nuclear factors. RAW 264.7 cells were treated with PCA for 2 h and cultured with RANKL for the corresponding time. (A) Western blotting was used to analyze the total protein extracts of proteins associated with the MAPKs and Akt signaling pathways. Phosphorylation of MAPKs (ERK, p-38 and JNK) and Akt was quantified. (B) Western blotting was used to analyze the expression of p65, c-Fos and NFATc1. All data represent at least three independent experiments. Values represent the mean ± SEM. **P<0.01 vs. sham; #P<0.05, ##P<0.01 vs. RANKL. MAPK, mitogen-activated protein kinases; NFATc1, nuclear factor of activated T cells 1; p, phosphorylated; PCA, protocatechuic acid; RANKL, receptor activator of nuclear factor-κB ligand.