DDR1 and metastatic malignant neoplasm: To validate their unique localization within ASMCs, an antibody against alpha smooth muscle actin (α-SMA) was used to outline ASMCs by immunofluorescence staining (Fig. 4d; red color, and Supplementary Fig. 5e, f), and anti-CD167a was used to mark the relative localization of metastatic cancer cells (Fig. 4d; green color, and Supplementary Fig. 5e, f).