β-Catenin–dependent activation of ERK is required for the maintenance of NK-cell survival by fibronectin. (A) Mitogen-activated protein kinases pathway in NK cells cultured in the presence of fibronectin was analyzed by Western blot. (B) Analysis of β-catenin, Src, p-ERK, and Bcl-2 in NK cells derived from littermate control (β-catenin^{floxed/floxed}) or β-catenin^−/− mice and cultured in the presence of fibronectin. (C) Expression of Bcl-2 in NK cells cultured in the presence of fibronectin with or without pretreatment of PD98095 was tested by Western blot. (D) NK cells were pretreated with PD98095 or U0126 for 30 minutes, then cultured in the presence of fibronectin for the indicated times and viability of NK cells was analyzed using FACS. Data are shown as 1 typical result from 3 independent experiments with similar results or as mean ± SD of 3 independent experiments. *P < .05.