Immunohistochemical staining revealed that the HMGB3 protein was expressed at low levels in the lung tissue of normal mice treated with saline but was increased in mice with silicosis (red arrowheads) (Fig. 6J); this protein was mainly expressed in infiltrating macrophages (CD68, yellow arrowheads) (Fig. 6K) rather than in myofibroblasts (α-SMA, green arrowheads) (Fig. 6L). This evidence concerns the gene CD68 and silicosis.