Figure 1: Fluorescence image and spectra. A, NADH fluorescence image and spectra of control cells (72 hrs); B, NADH fluorescence image and spectra of VEGF treated cells (72 hrs); C, Tryptophan fluorescence image and spectra of control cells (72 hrs); D, Tryptophan fluorescence image and spectra of VEGF treated cells (72 hrs). There were no difference between the VEGF treated and control cells, which suggested that application of the growth factor of VEGF does not cause the abnormal cell metabolism