Source:http://linkedlifedata.com/resource/umls/id/C1155065
GO: The change in morphology and behavior of a mature or immature T cell resulting from exposure to a mitogen, cytokine, chemokine, cellular ligand, or an antigen for which it is specific. [GOC:mgi_curators, ISBN:0781735140],NCI: T-Cell Activation involves stimulation of T lymphocytes by receptor interaction with mitogens or cell surface-displayed antigens resulting in biosynthesis of lymphokines, cell proliferation, cell differentiation, and maturation to support immune activity.