has subject area 1-Methyl-3-isobutylxanthine Aphidicolin Calmodulin Cells, Cultured Cyclic AMP Diterpenes Histocompatibility Antigens Class I Humans Interleukin-2 Lymphocyte Activation Lymphocytes Pentoxifylline RNA, Messenger Receptors, Interleukin-2 Receptors, Transferrin