Induction of proliferation in the ER/EB2-5 cells by hIL-10 in the absence of EBNA-2 expression. (A) Immunoblot analysis of LMP-1, EBNA-2, c-myc, cyclin E, and β-actin expression in total ER/EB2-5 cell lysates. The cells were starved of estrogen for 3 days before the addition of hIL-10 and then harvested at the indicated time points. Total cell extracts of DG75 cells were analyzed as controls for c-myc and cyclin E expression. (B) Proliferation of the estrogen-starved ER/EB2-5 cells in the presence of hIL-10 as measured by 12-hour incorporation of radioactive thymidine. □ indicates estrogen-treated cells; ▪, nontreated cells; and , IL-10-treated cells. The mean CPM was calculated from 3 independent experiments. The error bars indicate ± SD. (C) Immunoblot analysis of LMP-1 and β-actin expression in P3HR1 virus-infected tonsillar B cells. Total cell lysates were prepared 24 hours after infection and treatment with 50 ng/mL hIL-10 or 20 ng/mL PMA.