Figure 1.

Methotrexate pretreatment stimulates the accumulation of PpIX in LNCaP cells. LNCaP cells, seeded in 35 mm dishes 1 day previously, were incubated in culture medium containing MTX (1 mg l⁻¹; +MTX), or in medium without additives (−MTX). After 72 h, ALA was added to some of the dishes (0.3 mM, +ALA; middle and right panels) and the cells were incubated for an additional 4 h. Protoporphyrin IX-specific fluorescence was analysed by fluorescence microscopy (see Materials and Methods). Upper panels: phase-contrast images. Lower panels: PpIX-fluorescent images. Scale bar, 50 μm.