Fig. 6. Dose-dependent internalization of OGRNase A and OGONC. (A) HeLa cells were grown on coverslips in the wells of a six-well plate, incubated with 30% labeled OGRNase A or OGONC (0.01, 0.1, 1 and 10 µM), washed, and fixed as described for Fig. 5. The arrows correspond to the IC₅₀ values for G88R RNase A and ONC (Table 2). (B) HeLa cells were pulsed with OGRNase A (circles) or OGONC (squares) as described for A, except that cells were treated with trypsin before fixation. Fluorescence was quantified using a FACScan flow cytometer. Each data point represents the mean (±s.e.) of the fluorescence from 10,000 cells in two separate experiments.