Figure 4.

Primary transformants from Ink4a/ARF^−/− mice display low levels of apoptosis. Primary pre-B transformants from Ink4a/ARF^−/− and wild-type mice were stained with MC540 within a week of culture in liquid medium. Each histogram represents analysis of a single primary transformant. The data shown are representative of analyses of 15 primary transformants from each type of mouse. The controls are healthy, established pre-B cell transformants (Top Left) and pre-B transformants treated with γ-irradiation 8 hr before analysis (Bottom Left). The percentages of MC540-stained cells are indicated.