Polycomb Silencing in MM Figure 2. Polycomb target genes are enriched for H3K27-tri-methylation in MM patient cells and MM cell lines. Chromatin immunoprecipitation (ChIP) assay using (A)–(D): antibody against H3K27-tri-methylation in purified CD138+ cells from MM patients; (E) and (F): antibodies against H3K27-tri-methylation and H3K9-acetylation in RPMI 8226 and U-266-1984 cells. The RPL30 and GAPDH genes were used as a negative control for H3K27-tri-methylation and a positive control for H3K9-acetylation. The CIITA, CXCL12, GATA2, CDH6 and ICSBP genes were selected from the integrative genomics profile. * The INK4A gene was selected from the literature. Immunoprecipitated DNA was analyzed using real- time qPCR. Specific signal was calculated as fold change between signal and background (IgG) noise normalized to percent input. (E) and (F): Error bars represent SD from three independent biological experiments. doi:10.1371/journal.pone.0011483.g002 PLoS ONE | www.plosone.org 4 July 2010 | Volume 5 | Issue 7 | e11483