However, there were significantly fewer α-SMA+ fibroblasts in shPdgfc metastatic lesions following intravenous inoculation of TSAE1 or HRM1 cells (Fig. 5e,f and Extended Data Fig. 9c), indicating that, in the young lung microenvironment, tumor-derived PDGF-C is required to promote fibroblast recruitment and activation. The gene discussed is PDGFC; the disease is neoplasm.