Figure 1

S and G1 cell cycle distributions in murine liver cells at different stages of development. (A) Single liver cells were isolated from mice at the embryonic stages E11.5, E13.5, E15.5, and E17.5 and at postnatal days 0, 7, 14, 21 and 56, and were then fixed. The DNA content of PI-stained nuclei was determined by flow cytometry. The cells in the G1, S, and G2/M phases were analyzed (Modfit software) and graphed to determine the distribution pattern during murine development. The mean ± SD was from 2 independent experiments. The S-phase cells were dominant at early stages of development. Starting at E17.5, the G1 population started to increase while the S population decreased. (B) Representative histograms of the cell cycle distribution of murine liver tissue at indicated stages. In adult mice (P56), most liver cells were in the G1 cell phase. (C) Liver tissue lysates from mice at the indicated stages of development were prepared for WB analysis of Cdk1, Cdk2 and Cdc25A, and the cyclins D1, E, A, and B1 with β-actin as the loading control. (D) WB analysis of the Cdk inhibitors p21 and p27.