Phorbol esters induce interleukin 2 mRNA in sensitive but not in resistant EL4 cells.

Effects of protein kinase C activators on phorbol ester-sensitive and -resistant EL4 thymoma cells.

Phorbol ester-sensitive EL4 murine thymoma cells respond to phorbol 12-myristate 13-acetate with activation of ERK mitogen-activated protein kinases, synthesis of interleukin-2, and death, whereas phorbol ester-resistant variants of this cell line do not exhibit these responses. Additional aspects of the resistant phenotype were examined, using a newly-established resistant cell line. Phorbol e...

Activation of messenger-independent protein kinases in wild-type and phorbol ester-resistant EL4 thymoma cells.

Phorbol esters, acting via activation of the protein kinase C family of protein serine/threonine kinases, are able to exert profound effects on various cellular functions. In this study, we used the EL4 thymoma cell line to study the potential role of "downstream" protein serine/threonine kinases in cellular responses to phorbol esters. In wild-type EL4 cells, addition of phorbol ester caused a...

Phorbol Esters Induce Differentiation of Human

RasGRP1 confers the phorbol ester-sensitive phenotype to EL4 lymphoma cells.

The murine EL4 lymphoma cell line exists in variants that are either sensitive or resistant to the tumor promoter phorbol 12-myristate 13-acetate (PMA). In sensitive EL4 cells, PMA causes robust Erk mitogen-activated protein kinase activation that results in growth arrest. In resistant cells, PMA induces minimal Erk activation, without growth arrest. PMA stimulates IL-2 production in sensitive,...

cAMP inhibits induction of interleukin 2 but not of interleukin 4 in T cells.

In this report, we explore the nature of the inductive stimuli leading to expression of the divergently regulated lymphokines interleukin 2 (IL-2) and interleukin 4 (IL-4). Elevation of cAMP levels blocks IL-2 induction while sparing IL-4 induction. These effects are gene-specific, not cell-specific, and can be observed in the same cells. Transient transfection experiments using murine IL-2 reg...