Disclosed is an in vitro assay for evaluating cellular activity, in which a culture is provided that contains one or more histologically different isolated mammalian cell-line that stably and constitutively express fluorescent proteins having a different emission spectra. The culture is assessed for cellular activity by quantifying fluorescence or detecting a pattern of fluorescence from fluorescent proteins present in the culture. In some embodiments, the cellular activity of the cell-lines is assessed by determining one or more of the growth rate, migration potential, or tubule formation potential of the cell-lines using the quantified fluorescence or pattern of fluorescence. Also disclosed are cell-lines have been stably transfected with mammalian expression plasmids that constitutively express different fluorescent proteins. Kits for performing the disclosed assays, which include the disclosed fluorescent cell-lines, are also disclosed.