siRNA knockdown of STAT3 blocked macrophage-induced expression of breast cancer proliferative genes cyclin D1 and c-Myc, and of cytokines IL-6, CCL5, and MCP-1 (Figure 6d), demonstrating the essential role of STAT3 expression in conditioned macrophage-induced alteration of gene expression. Here, CCND1 is linked to breast carcinoma.