Source:http://linkedlifedata.com/resource/umls/id/C1155003
GO: The change in morphology and behavior of a mature or immature B 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: A set of events occurring in B lymphocytes following stimulation with cognate antigen. Crosslinking the B cell antigen receptor (surface immunoglobulin) leads to increased expression of MHC class II molecules, exit from the resting state (G0) into the G1 phase of the cell cycle, and in the case of a strong antigenic stimulus, proliferation.