CF®640R-cAMP is a fluorescently labeled cAMP analog. Single molecules of fluorescently labeled cAMP have been imaged bound to the cAMP receptor on the surface of Dictyostelium cells. CF® dyes are Biotium's line of next-generation fluorescent dyes with advantages in brightness, photostability, and conjugate specificity compared to other fluorescent dyes. Far-red fluorescent CF®640R has excitation/emission at 642/662 nm.