Oscillation of phosphorylation of the p110RB protein during the different stages of the cell cycle. CV-1P cells (A) and T24 cells (B) were synchronized in G0/G1 by density arrest and then allowed to enter the cell cycle by sparsely replating cells in fresh medium. Equal numbers of cells were seeded into about 50 culture dishes (3 × 106 cells per dish) and were allowed to grow to time points of 18 to 34 h. One entire plate was harvested for each lane on the Western blot. A second batch of dishes (1.5 × 106 cells per dish) was plated 16 h later than the first and was harvested for hours 2 to 16. Again, each lane contained cells from one plate. At 2-h intervals after replating, cells were collected for cell cycle distribution analysis and RB protein determination. The percentage of cells in G1 (filled squares), S (filled circles), and G2/M (open squares) at each indicated time was determined by flow cytometry. RB protein was analyzed by immunoprecipitation followed by immunoblotting; five RB bands could be distinguished. The sudden change in signal intensity in CV-1P and T24 cells is due both to a decrease in the number of cells seeded for hours 2 to 16 and to random variability in the counting of different batches. (Reprinted by permission from Chen et al., Cell, vol. 58, pp. 1193–1198, copyright 1989, Cell Press.) Source: Retinoblastoma, The Online Metabolic and Molecular Bases of Inherited Disease Citation: Valle D, Beaudet AL, Vogelstein B, Kinzler KW, Antonarakis SE, Ballabio A, Gibson K, Mitchell G. The Online Metabolic and Molecular Bases of Inherited Disease; 2014 Available at: https://ommbid.mhmedical.com/DownloadImage.aspx?image=/data/books/971/ch36fg14.png&sec=62666636&BookID=971&ChapterSecID=62666500&imagename= Accessed: November 04, 2017 Copyright © 2017 McGraw-Hill Education. All rights reserved