Fig. 1. Down-regulation of protein kinase CK2α leads to decreased proliferation rate and delayed G1/S cell cycle transition. (A) H9c2-CK2α-44 cells were seeded in 96-well plates (1000 cells/well) in the absence (Control) or presence of 1 μg/ml doxycycline (+ Dox) in order to induce down-regulation of CK2α in the cells. Cell growth was analyzed with the Incucyte S3 live-cell analysis system. Data represent mean values +/- standard deviation (STDEV) of n = 8 experiments and expressed in percentage, *P<0.0001. Insert: western blot analysis of whole cell lysate from control cells or cells treated with doxycycline for the indicated times. Western blot membranes were incubated with antibodies against CK2α and β-actin, respectively. Detection of β-actin served as loading control. (B) The cell cycle profile of cells expressing or lacking CK2α induced in the presence of doxycycline for the indicated times was determined by flow cytometry analysis following propidium iodide staining. The experiments were repeated three times. Average values are expressed in percentage +/- STDEV.