Relationship between Mcl-1 transcripts, proteins, and RNA polymerase II phosphorylation status. (A) Mcl-1 protein levels were related to Mcl-1 mRNA in CLL cells after incubation with 3 μM flavopiridol for 2, 4, 24, and 48 hours (n = 25, P < .001, r = 0.75). The mRNA and protein levels were expressed as percentages of controls incubated with DMSO. (B) Mcl-1 mRNA levels were related to the phosphorylation of RNA polymerase II CTD at Ser2 (pSer2-Pol II) in CLL cells after incubation with 3 μM flavopiridol for 2, 4, 24, and 48 hours (n = 25, P = .006, r = 0.54). (C) Mcl-1 protein levels were related to the phosphorylation of RNA polymerase II CTD at Ser2 (pSer2-Pol II) in CLL cells after incubation with 3 μM flavopiridol for 2, 4, 24, and 48 hours (n = 25, P = .004, r = 0.56). Solid line indicates linear regression of data points (•).