IL6 and breast cancer: In breast cancer, this pathway was altered by the following mechanisms: [17] (1) down-regulation of phosphotyrosine specific phosphatases; [18] (2) down-regulation of negative regulators of STAT; [19] (3) an increase in the amount of IL-6; [20] and (4) activation of other upstream oncogenic pathways, such as c-Src, ERBB1, or PI3K/ mTOR.