Pharicin B enhances ATRA-regulated gene expression in NB4 cells. (A) NB4^FLAG-RARα cells were treated as indicated, and ChIP experiment was performed as described in the Methods. NB4^NC cells were used as the negative control. (B) NB4 cells were treated by 2μM pharicin B and/or 10⁻⁸M ATRA for 48 hours, and the expression of genes, as indicated, were detected by real-time PCR with specific primers. P values between pharicin B plus ATRA and ATRA are shown. Each experiment was repeated 3 times.