Figure 5.

Effect of bafilomycin A₁ treatment on the uptake of ¹⁴C-carboplatin (A) and HRPO (B) by CP-r and CP-s cells. Cells were washed twice with prewarmed serum-free DMEM and incubated at 37°C with the same medium in the presence (+) or absence (−) of 1 μM bafilomycin A₁. After 30 min medium was removed and fresh DMEM containing ¹⁴C-carboplatin (2 μCi ml⁻¹) or HRPO (2 mg ml⁻¹) with (+) or without (−) bafilomycin A₁ was added. Then the incubation was continued at 37°C in a CO₂ incubator. After 1 h for ¹⁴C-carboplatin uptake and 2 h for HRPO uptake, cells were processed as described in Materials and Methods. Values are mean ±s.d. from three independent experiments.