Interleukin-4 (IL-4) is a lymphokine with profound effects on the growth and differentiation of immunologically competent cells. IL-4 is also known as B cell stimulatory factor-1 (BSF-1), T cell growth factor-2 (TCGF-2) and mast-cell growth factor-2 (MCGF-2). Inhibits VEGF-induced and FGF-Basic-induced angiogenesis. IL-4 is a complex glycoprotein released by a subset of activated T cells. Treatment of IL-4 with specific glycosidases yields an active polypeptide. Human and mouse IL-4 share 50% amino acid sequence homology, but their biological actions are species-specific.