To elucidate whether damaged/activated fibroblasts are present in non-tumor-bearing chemotherapy-treated mice, lung sections from vehicle or chemotherapy-treated mice were co-stained for p21 alongside cell-type markers for myofibroblasts (alpha-smooth muscle actin, αSMA), epithelial cells (EpCAM), and endothelial cells (endomucin) (Figure 3A). The gene discussed is CDKN1A; the disease is neoplasm.