Figure 4.

Pretreatment of LNCaP cells with MTX enhances cytotoxicity after the addition of ALA and light. Survival was measured by MTT dye conversion (A and B) or by colony formation (C and D), and presented in two ways. Raw data from a single, typical experiment are shown (A and C), followed by the per cent survival (relative to unirradiated controls), pooled from multiple experiments (B and D). In all cases, cells were preconditioned for 72 h with MTX (1 mg l⁻¹; triangles) or medium alone (circles), then incubated with ALA (0.3 mM) for 4 h and irradiated with light. (A) MTT dye assay at 24 h, single experiment. (B) MTT dye assay, pooled experiments. Mean±s.e.m. of four experiments. (^*), P<0.05. (C) Colony formation assay at 13-day, single experiment. (D) Colony formation assay at 13-day, pooled experiments. Mean±s.e.m. of four experiments. (^**), P<0.0005. See Materials and Methods and Results for further details.