STAT3 and neoplasm: To confirm that MCF7 cells were capable of signaling through IL-6, we exposed MCF7 cells for 30 min to CM from PGE2 or EtOH treated fibroblasts of differing tumor-promoting capabilities, in the presence of an IL-6 neutralizing antibody or goat IgG control, and immunoblotted for the levels of phosphorylated STAT3 as an indicator of the IL-6 signaling pathway.