Evaluation of FCM analysis of GR binding by RLBA. Analysis of GR binding in (a) K562 and (b) U937 with and without 10-6 M Dex by FITC-Dex-FCM and RLBA. Parallel FCM-FITC-Dex and radiometric assays were performed on the same day, using the same cell cultures to minimise variation. Specific FCM analysis was obtained as difference of mean channel number between total and nonspecific binding. By linear regression analysis, a positive correlation between results from the two methods was found. Dex = dexamethasone; FCM = flow cytometry; FITC = fluorescein isothiocyanate; GR = glucocorticoid receptor; RLBA = radiolabelled receptor ligand.