About SOX21
SRY-related HMG-box (SOX) genes encode a family of DNA-binding proteins containing a 79-amino acid HMG (high mobility group) domain that shares at least 50% sequence identity with the DNA-binding HMG box of the SRY protein (MIM 480000). SOX proteins are divided into 6 subgroups based on sequence similarity within and outside of the HMG domain. For additional background information on SOX genes, see SOX1 (MIM 602148).[supplied by OMIM, Apr 2004]

About PE
Phycoerythrin (PE, R-PE) is a red-emitting fluorescent protein-chromophore complex that can be excited the 488-nm blue, 532-nm green, or 561-nm yellow-green laser with increasing efficiency and captured with a 586/14 nm bandpass filter. PE has an excitation peak at 565 nm and an emission peak at 578 nm. PE is 240kD in size and has an extinction coefficient of ~2x10^6 which makes it one of the brightest fluorophores available and a potent donor upon which to build tandem fluorophores with longer Stoke's Shifts.