CD45RC is a 200-220 kD single chain type I membrane glycoprotein. It is an exon 5 splice variant (exon C) of the tyrosine phosphatase CD45. The CD45RC isoform is expressed on B cells, majority of CD8+ T cells and a subset of CD4+ T cells, but not on myeloid cells. CD45 and its isoforms non-covalently associate with lymphocyte phosphatase-associated phosphoprotein (LPAP) on T and B lymphocytes. CD45 has been reported to be associated with several other cell surface antigens, including CD1, CD2, CD3, and CD4. CD45 is involved in signaling lymphocytes activation.