Cul4A protein loss in bone marrow following in vivo Cul4A deletion leads to apoptosis and altered cell cycle distribution. Mutant mice (closed bars or symbols) and controls (open bars or symbols) were induced with pIpC, and 48 hours later LDMNCs were harvested from femurs and plated in vitro. At each time point, cells were collected and analyzed by (A) annexin V–positive, 7AAD-negative staining, (B) TUNEL assay, and (C) DNA content for cell-cycle distribution. Asterisks denote time points where mutant and control differences were statistically significant (P ≤ .04). Cells for these assays were cultured under identical conditions or were assayed simultaneously for apoptosis (A,B) or cell-cycle distribution (C), so results for corresponding time points are comparable. For panel C, ■ and □ represent average percentage cells in G0/G1-phase, and ▴ and ▵ represent average percentage cells in S-phase. Results from independent experiments were combined: 4 for panel A, 2 for panel B, and 3 for panel C. M indicates mutant; C, control.