Recruitment of elongation competent Ser2P RNA pol II to the β-globin locus during mouse MEL cell differentiation. (A) The mouse β-globin locus is diagrammed, and the positions of TaqMan probes used for real-time PCR are indicated below and named on the graphs. (B) MEL cells were treated with 2% DMSO for 4 days (IMEL) or without DMSO (UMEL), and globin mRNA was analyzed by quantitative real-time RT-PCR. Data are mean ± SEM, and 18S ribosomal RNA transcripts served as a control. (C-D) ChIP was performed MEL cell chromatin and antibodies to (C) RNA pol II or (D) Ser2P pol II. Three different chromatin preparations were analyzed by quantitative PCR. Error bars represent the SEM. Necdin, not transcribed in these cells, served as a negative control.