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Nat Immunol. 2000 Nov;1(5):419-25.

Pivotal role of phosphoinositide-3 kinase in regulation of cytotoxicity in natural killer cells.

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Immunology Program, H. Lee Moffitt Cancer Center, Department of Interdisciplinary Oncology, University of South Florida College of Medicine, Tampa, FL 33612, USA.

Erratum in

  • Nat Immunol 2000 Dec;1(6):541.


The mitogen-activated protein kinase-extracellular signal-regulated kinase signaling element (MAPK-ERK) plays a critical role in natural killer (NK) cell lysis of tumor cells, but its upstream effectors were previously unknown. We show that inhibition of phosphoinositide-3 kinase (PI3K) in NK cells blocks p21-activated kinase 1 (PAK1), MAPK kinase (MEK) and ERK activation by target cell ligation, interferes with perforin and granzyme B movement toward target cells and suppresses NK cytotoxicity. Dominant-negative N17Rac1 and PAK1 mimic the suppressive effects of PI3K inhibitors, whereas constitutively active V12Rac1 has the opposite effect. V12Rac1 restores the activity of downstream effectors and lytic function in LY294002- or wortmannin-treated, but not PD98059-treated, NK cells. These results document a specific PI3K-->Rac1-->PAK1-->MEK-->ERK pathway in NK cells that effects lysis.

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