CDK9 regulates phosphorylation of proteins involved in mRNA processing and splicing. (A) MV4-11 cells were treated with atuveciclib for 1 hour and then analyzed for global phosphorylation changes, using phosphoproteomic LC-MS/MS. Proteins that exhibited significant downregulation of phosphorylation upon atuveciclib treatment were annotated using Metascape. The heat map identifies the pathways most significantly affected. (B) MV4-11 cells were treated with atuveciclib for 1 hour, and then global phosphorylation changes were analyzed using phosphoproteomic LC-MS/MS. Proteins that exhibited significant upregulation of phosphorylation upon atuveciclib treatment were annotated using Metascape. The heat map identifies the pathways most significantly affected. (C) List of proteins whose phosphorylation status was downregulated by atuveciclib treatment and were also identified as potential binders to either mLST8 or CDK9.