TGFB1 and neoplasm: While in non angiogenic islets an exclusively cytoplasmic staining was observed in some cells, within angiogenic islets pSMAD3 expression and nuclear localization was recurrently detected in some tumor cells but also more strikingly in both αSMA-positive fibroblasts and F4/80-positive macrophages (Fig. 2, D and E), demonstrating that these stromal cells undergo canonical TGF-β signaling in the angiogenic islets.