The Vgamma9 TCR is a variant of the TCR gamma chain expressed on a subset of gamma/delta T cells. Vgamma9Vdelta2 T lymphocytes, a major gamma/delta T cell subset in humans, recognize phosphoantigens, certain tumor cells, and cells treated with aminobisphosphonates. This cell population displays cytolytic activity against various tumor cells. The gamma/delta TCR is a heterodimeric TCR complex composed of covalently bound gamma and delta chains involved in antigen recognition and the non-covalently associated monomorphic proteins CD3delta, gamma, epsilon, and zeta chains.