ETS1 regulates genes involved in B-cell differentiation. (A) RNA levels of BCL2, PAX5, BCL6, PRDM1, XBP1, and IRF4 and β2-microglobulin transcripts after ETS1 or FLI1 down-regulation were determined by real-time PCR (day 5). Histogram graphs represent the average of at least 3 independent experiments. *P value < .05. (B) Left: RNA levels of PRDM1, XBP1, and IRF4 and β2-microglobulin transcripts were determined by real-time PCR after concomitant ETS1 and FLI1 down-regulation (day 3). *P value <.05. Right: western blot analysis with antibodies against ETS1, PRDM1, IRF4, active splice form XBP1s, and GAPDH as loading control after shETS1 (day 5). (C) ETS1 reintroduction restores PRDM1 mRNA levels in OCI-Ly7. RNA levels of ETS1 and PRDM1 were determined by real-time PCR at 24 hours after ETS1 reexpression in cells previously interfered for ETS1 expression. *P value < .05. (D) Chromatin immunoprecipitation analysis of PRDM1 promoter performed with antibody against ETS1 in OCI-Ly7 infected with the control shGFP or shETS1 lentivirus. Input and immunoprecipitated DNA was amplified by quantitative real-time PCR using primers amplifying the Δ-1100/-939 bp region of the PRDM1 promoter. Enrichments are presented as percentage of total input DNA. Upper: western blot analysis of ETS1 after shRNA.