Figure 3

Confirmation of functional nitroreductase expression in HCT-116 cells using the fluorogenic probe FSL81. FSL81 is metabolised to a blue fluorescent product in HCT116 cells expressing nfsB_Pa, nfsA_Ec or nfsB_Ec, but not in untransfected wild type (WT) cells. Cells were plated at a density of 50,000 cells per well in a 24 well plate containing fresh αMEM media amended with 5% fetal calf serum. After 3 h media was aspirated and replaced with fresh media containing 50 μM FSL81, followed by incubation for a further 2 h. Images are relief phase (left) or fluorescence mode (right; excitation 390/40 nm, emission 446/33 nm) taken using an EVOS^® Floid^® Cell Imaging Station (Invitrogen, Carlsbad, CA).