Figure 4. (A) Protein expression of p-ERK1/2, t-ERK1/2, MMP-1, MMP-3, IL-1β and TNF-α in monocyte-macrophage cells was detected by Western blot (ERK: extracellular signal-regulated kinase; MMP: matrix metalloproteinase; IL-1β: interleukin-1β; TNF-α: tumor necrosis factor α). (B) Statistical histogram of relative protein expression.