Fig. 5. LOF of KIF20A in mouse tumor cells inhibits proliferation by inducing cell cycle exit.

a Two tumor cell lines were derived from the Ptc single-knockout mice and these cells carried a genotype of Ptc^−/−; Kif20a^+/+. Two tumor cell lines from the Ptc/Kif20a double-knockout mice were also established in culture and these cells showed a genotype of Ptc^−/−; Kif20a^fl/−. The latter two tumor lines displayed slower proliferation rates. Individual data points represented replicates of cell samples. Data are mean ± SD. P = 9.46E − 05 (two-way ANOVA). b Proliferating tumor cells were labeled with EdU for 24 h and were then stained for EdU and Ki67. There were fewer Ki67⁺ cells and a relatively high percentage of EdU⁺Ki67⁻ cells (in the total population of EdU⁺ cells) in the tumor line derived from the Ptc/Kif20a double-knockout mice. Scale bar represents 50 μm. Data are mean ± SD. P = 5.45E − 08; 1.75E − 07 (Student’s t-test). c Tumor cells (having a genotype of Ptc^−/−; Kif20a^fl/−) derived from the Ptc/Kif20a double-knockout mice were infected with lentivirus expressing Cre-2A-GFP or control GFP and were next labeled with EdU for 24 h in culture. Knockout of the remaining Kif20a allele in these cells resulted in cell cycle exit. Scale bar represents 50 μm. Data are mean ± SD. P = 4.12E − 05 (Student’s t-test). d Tumor cells derived from the Ptc/Kif20a double-knockout mice were infected with lentivirus expressing Cre-2A-GFP or control GFP. After labeling with propidium iodide, the cells were examined for their DNA contents by flow cytometry analysis. PI, propidium iodide; 2N, cells in G1 phase; 4N, cells in G2/M phase or bi-nucleated cells. n.s., not significant.