Inhibition of Cdk9, the phosphorylation unit of polymerase II at Ser2, leads to a decreased transcription of anti-apoptotic proteins like Mcl-1 and Bcl-2, which subsequently induces apoptosis in endometrial cancer cells.14 This could also be shown in CCA cells, where dinaciclib treatment leads to a decrease in Bcl-xL and Bcl-2 expression and thus induces cell death.4 Our results support the findings of other researchers, as we demonstrated a decreased level of the anti-apoptotic protein Mcl-1 and reduced phosphorylation at Ser64 following dinaciclib treatment.14 Here, MCL1 is linked to cholangiocarcinoma.