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 PerCP
Peridinin-Chlorophyll-Protein (PerCP) is a red-emitting fluorescent protein isolated from algae that can be excited by the 488 nm blue laser and captured with a 670/30 nm bandpass filter. PerCP exhibits a large Stokes' Shift, with an excitation peak at 482 nm and an emission peak at 675 nm. PerCP is was historically used in flow cytometry, however it is highly susceptible to photobleaching and has poor stability. Alternatives like BB700, NovaFluor Blue 690 or PerCP-eFluor™ 710 are preferred. PerCP is a generic dye that has no sole manufacturer.