TGFB1 and cancer: Since TGFβ-1 gene, mRNA, and protein are mostly secreted by macrophages and fibroblasts of tumor stroma, steady levels of this dual-action marker, might be an index of the activity of the primary cancer signaling following a short duration of NNK induction in female rats, before the formation of tumor masses, as observed in the present study [35], [36] (Fig. 1E).