Survival curves of Rat-1 cells and subline 1302 exposed to either ara-C (top panels) or DNR (bottom panels) after 24-hour treatment with ATRA (10⁻⁷ mol/L).

For the parental cells, there was no significant change in D10 (A) or the cells became more resistant (C). For 1302 cells, D10 values were decreased significantly after ATRA for cells exposed to ara-C (B) or DNR (D). Results with R2,2 cells were similar to the parental controls and are not shown.