About IL-21
This gene encodes a member of the common-gamma chain family of cytokines with immunoregulatory activity. The encoded protein plays a role in both the innate and adaptive immune responses by inducing the differentiation, proliferation and activity of multiple target cells including macrophages, natural killer cells, B cells and cytotoxic T cells. Dysregulation of this gene plays a role in multiple immune-mediated diseases including lupus, psoriasis and chronic inflammatory diseases. Alternatively spliced transcript variants encoding multiple isoforms have been observed for this gene. [provided by RefSeq, Dec 2011]

About Alexa Fluor 680
Alexa Fluor™ 680 (AF680, Alexa 680) has an excitation peak at 679 nm and an emission peak at 702 nm, and is spectrally similar to Cy®5.5 (GE Healthcare), IR680® (Licor), iFluor® 680 (ATT Bioquest) and iFluor® 700 (ATT Bioquest). Alexa 680 is commonly used for flow cytometry, fluorescence microscopy and super-resolution microscopy.