Expression profiles of endogenous ZBP-89 protein and mRNA and CD11b mRNA during differentiation of U937.

(A) Morphology of U937 cells without (left panel) and with PMA treatment for 72 hours (right panel). The later cells form readily visible clusters (original magnification, × 40). (B) Real-time RT-PCR analysis of CD11b and ZBP-89 during U937 cell differentiation. The experiment was performed using total RNA isolated from U937 cells treated with PMA (100 ng/mL) for 0, 24, 48, and 72 hours. The ratios CD11b/GAPDH or ZBP-89/GAPDH in untreated U937 cells (0 h) were given a value of 1, and the ratios at 24, 48, and 72 hours are displayed as fold above 1. (Inset) Thirty micrograms of nuclear extract from U937 cells treated with PMA (100 ng/mL) for 0 (lane 1), 24 hours (lane 2), 48 hours (lane 3), and 72 hours (lane 4) were resolved by 6% SDS-PAGE. Proteins were transferred to a nitrocellulose membrane and analyzed with an anti–ZBP-89 antibody followed by chemiluminescence. ZBP-89 protein is indicated with an arrow.