MDA-MB-231 human breast adenocarcinoma cells (American Type Culture Collection, Manassas, VA) were cultured in L-15 Leibovitz’s Medium (Mediatech, Manassas, VA) supplemented with 10% fetal bovine serum (FBS) (Atlanta Biologicals, Flowery Branch, GA) at 37 °C with atmospheric CO2. The human foreskin fibroblast (HFF) cell line (ATCC) was cultured in Dulbecco’s Modified Eagle Medium (DMEM) with 10% FBS at 37 °C in a humidified chamber with 5% CO2. Human cytomegalovirus strain AD169 (ATCC) was used to infect confluent monolayers of HFFs at the indicated multiplicities of infection. Purified recombinant cmvIL-10, human IL-10, and epidermal growth factor (EGF) were purchased from R&D Systems (Minneapolis, MN). IL-10R neutralizing antibody and S3I-201 Stat3 inhibitor were from Santa Cruz Biotechnology (Santa Cruz, CA).