Dose response and time course of FR-β induction by ATRA in KG-1 cells.

(A) KG-1 cells were grown in the presence of the indicated concentrations of ATRA for 5 days. Crude membranes from the treated cells were probed by Western blot with the use of rabbit antihuman FR-β antibody and alkaline phosphate (AP)–conjugated goat-antirabbit secondary antibody. (B) KG-1 cells were grown in the presence of ATRA as in panel A. On day 5, cells were washed with PBS and stained with anti–FR-β antibody and FITC-conjugated secondary antibody and then examined by flow cytometry. (C) KG-1 cells were treated with 1 μmol/L ATRA for different periods, and cell surface FR-β expression was quantitated by flow cytometry as in panel B. (D) KG-1 cells were grown in the absence (lane 1) or presence (lane 2) of 1 μmol/L ATRA for 5 days, and the cell lysates analyzed by Western blot. Alternatively, the ATRA-treated cells were washed and resuspended in medium without ATRA and grown for a further 7 days before Western blot analysis of the cell lysates (lane 3). The Western blot was probed with rabbit anti–FR-β antibody and AP-conjugated secondary antibody.