Cellular autofluorescence--is it due to flavins?

For many cell types, cellular autofluorescence in the 500-600 nm spectral region can result in a significant background signal for measurements of weakly fluorescent probes. Measurements of fluorescence intensity and spectra of a variety of cell types and assays of neuronal homogenates are presented to demonstrate that this autofluorescence is most likely due to endogenous flavoproteins.