Interleukin 2 induces rapid phosphorylation of cellular proteins in murine T-lymphocytes

When quiescent murine T-lymphocyte cells were stimulated by the addition of interleukin 2 (IL-2), they reinitiated DNA synthesis after a lag period of 5 h. Under these conditions, rapid but transient phosphorylation of two cellular proteins with Mr values of 27 000 and 26 000 was detected; maximal phosphorylation occurred within 10-15 min after the addition of IL-2. The protein of Mr 27 000 contained phosphoserine, while the protein of Mr 26 000 contained phosphothreonine.