TGFB1 and cancer: To determine the amount of active TGF-β in the tumor, we used pSMAD2/3 as a surrogate measure for TGF-β signaling, and observed an increased percentage of pSMAD2/3+ mCerulean- tumor micro-environmental, but not mCerulean+ A375 cancer cells, when comparing TS2/16 treatment to IgG treatment (Fig 1E and 1F).