This protocol can be applied to any strain of cell that can be safely run through a flow cytometer. For clarity, we have written it assuming E. coli DH5-alpha; to apply the protocol to another cell type, substitute the other cell type for any place where the protocol says [E. coli DH5-alpha].This protocol has been written for measurement of GFP, YFP, or other yellow\/green fluorescent proteins into MEFL units. To apply it to fluorescent proteins of other colors:Replace BBa_J364001 with a construct for strong expression of the other protein. For blue proteins (e.g., mTagBFP), measure with 405nm excitation and 450nm\/50nm emission filter. Units will be MEC30.For red\/orange proteins (e.g., mCherry), measure with 561nm excitation and 610nm\/20nm or 620nm\/15nm emission filter. \u00a0Units will be MEPTR.For far-red \/ near-infrared proteins (e.g., IRFP), measure with 635nm excitation and 780nm\/60nm or 750nm long-pass (LP) emission filter. Units will be MEAPCY7.To apply the protocol to multiple colors, add a positive process control for each color and use one of the tools on the iGEM Measurement Resources page to compensate measurements for spectral overlap.This protocol can be combined with bead-based cell size calibration.