Figure 3. Zt/f2 treatment induces apoptosis and cell cycle arrest. Raji cells were treated with macrophage-stimulating protein (MSP; 2 nM) in the presence or absence of Zt/f2 (2 nM) or control mouse immunoglobulin G (2 nM) for 72 h. (A) The proportion of early apoptotic cells in each quadrant is indicated. Data show that Zt/f2 treatment alone moderately increases the percentage of early apoptotic cells. A slight increase in the proportion of apoptotic cells is observed following combined MSP and Zt/f2 treatment. (B) Zt/f2 treatment induces G₁-phase cell cycle arrest in Raji cells. (C) Zt/f2 regulates the expression of apoptosis-related proteins in Raji cells. Treatment of Raji cells with Zt/f2 downregulates anti-apoptotic proteins (Mcl-1 and XIAP) and upregulates pro-apoptotic proteins (caspases 3 and 9, and poly [ADP-ribose] polymerase [PARP]). (D) Western blot analysis shows that expression of cyclins and cyclin-dependent kinases (cyclin D1, CDK4 and CDK6) are significantly reduced and p27 expression is significantly increased in Zt/f2-treated Raji cells.