Fig. 5.
Effect of TPA on the maturation of U937 and RU cells. (A) Cultures (5 × 105 cells) were grown in 5 mL of complete medium for 48 hours, in the absence (upper part) or presence (lower part) of 50 ng/mL of TPA, and harvested. Cell-surface antigen display and NAE activity were determined as described in Materials and Methods. Results shown are average values from three independent experiments (SD < 20%). (B) Homotypic aggregation of cells was visualized by phase contrast microscopy after incubation for 48 hours with TPA. U937 and RU cultures were indistinguishable from each other in the absence of TPA.
