Indeed, relative to normal tissues and DCIS (progressors) there was an infiltration of stromal mast cells and CD4 T-cells into DCIS (non-progressors) while the stroma of DCIS (progressors) showed enrichment of proliferating cancer-associated fibroblasts (CAFs) and collagen fibres [37]. The gene discussed is CD4; the disease is ductal breast carcinoma in situ.