TGFB1 and breast cancer: IL-11, a pleiotropic cytokine of the interleukin-6 type family [33], has been chosen as the “indicator” gene to investigate down-stream TGF-β signaling pathways, as reported for lung fibroblasts [30], periodontal ligament and gingival fibroblasts [34], and bone metastatic breast cancer cells [35].