The tumor burden weight in removed lungs from mice bearing 4T1/TGF-β1 tumors was greater than that of lungs from mice bearing 4T1/RFP tumors (P <0.001) (Fig. 1h), while the tumor weight at the primary site did not show a significant difference between the mice bearing 4T1/RFP cells and the mice bearing 4T1/TGF-β1 cells (P = 0.43) (Fig. 1g and Additional file 3: Figure S2). Here, TGFB1 is linked to neoplasm.