Analysis of cell cycle regulatory proteins. A. Approximately 10 μg of protein extracts of control and 5 μM and 20 μM ritonavir treated MDAH-2774 cells for 48 h were resolved by SDS-PAGE, transferred to nitrocellulose membrane; and probed with RB and E2F-1. β actin was used as a loading control. RB-p: hyper phosphorylated retinoblastoma protein; RB: Under phosphorylated retinoblastoma protein. MDAH-2774 cells treated with 15 μM ritonavir for 48 h were harvested and total RNA was isolated to generate cRNA and was hybridized to Whole Human Genome (G4112A) arrays (Agilent Technologies, Santa Clara, CA) according to the manufacturer's protocol. B. Analysis of RB family of pocket proteins. C. Analysis of E2F family of transcription factors. D, E and F represent the gene profile analysis of the expression of CDKs and Cyclins and CDKIs respectively that are involved in G0 to G1 phase transition.