Effects of RARα, RARβ, and RARγ selective retinoids on the expression of the toal TM an TF antigens in NB4 cells. NB4 cells were incubated with 0.01 μmol/L of Ro40-6055 (lane 2), Ro48-2249 (lane 3), Ro44-4753 (lane 4), or a combination of 0.005 μmol/L each of Ro40-6055 and Ro48-2249 (lane 5) for 24 hours. Total TM (A) and TF (B) antigen levels in cell lysates were measured by enzyme-linked immunosorbent assay, as previously reported.1 Results are shown as the means ± SD of three different experiments.