About CD69
This gene encodes a member of the calcium dependent lectin superfamily of type II transmembrane receptors. Expression of the encoded protein is induced upon activation of T lymphocytes, and may play a role in proliferation. Furthermore, the protein may act to transmit signals in natural killer cells and platelets. [provided by RefSeq, Aug 2011]

About PE-Fire 640
PE-Fire™ 640 from Biolegend is a red-emitting tandem fluorophore that combines pycoerythrin (PE) and Fire™ 640. The donor molecule, PE can be excited by the 488-nm blue, 532-nm green, or 561-nm yellow-green laser and and transfers energy to the acceptor molecule, Fire™ 640, which emitts light that can be captured with a 630/69 nm bandpass filter. PE-eF610 has an excitation peak at 565 nm and an emission peak at 639 nm. In spectral cytometry, this dye can be accurately unmixed from other dyes with highly overlapping spectral profiles, such as PE-Dazzle® 594 and PE-Cy5. PE-Fire™ 640 is recommended for labeling antigens that: (1) are expressed on a small subset (2) will be excluded from final analysis, and (3) require a bright signal but are not co-expressed with an antigen marked by a dye with overlapping spectra.