The receptor for interleukin 2 (IL 2) is induced on normal mature T cells activated by antigen or mitogen. Receptor-negative human T leukemic cell lines were induced to express the IL 2 receptor after incubation with 12-O-tetradecanoyl phorbol 13-acetate. The Mr of the IL 2 receptor expressed on the surface of four different T cell lines and normal peripheral blood lymphocytes varied. The source of the heterogeneity appeared to be due to differences in post-translational processing of the receptor. The precursor of the IL 2 receptor isolated from tunicamycin-treated HUT102B2 or 12-O-tetradecanoyl phorbol 13-acetate-induced CCRF-CEM cells had the same Mr and isoelectric point. Incubation of cells with 12-O-tetradecanoyl phorbol 13-acetate also induced the rapid phosphorylation of serine and threonine residues on the IL 2 receptor from HUT102B2 cells and activated peripheral blood lymphocytes. This phosphorylation may be mediated by the Ca2+ and phospholipid-dependent protein kinase C.