The Ca(2+)-regulated calcineurin/nuclear factor of activated T cells (NFAT) cascade controls alternative pathways of T-cell activation and peripheral tolerance. Here, we describe reduction of NFATc2 mRNA expression in the lungs of patients with bronchial adenocarcinoma. In a murine model of bronchoalveolar adenocarcinoma, mice lacking NFATc2 developed more and larger solid tumors than wild-type littermates. The extent of central tumor necrosis was decreased in the tumors in NFATc2((-/-)) mice, and this finding was associated with reduced tumor necrosis factor-alpha and interleukin-2 (IL-2) production by CD8(+) T cells. Adoptive transfer of CD8(+) T cells of NFATc2((-/-)) mice induced transforming growth factor-beta(1) in the airways of recipient mice, thus supporting CD4(+)CD25(+)Foxp-3(+)glucocorticoid-induced tumor necrosis factor receptor (GITR)(+) regulatory T (T(reg)) cell survival. Finally, engagement of GITR in NFATc2((-/-)) mice induced IFN-gamma levels in the airways, reversed the suppression by T(reg) cells, and costimulated effector CD4(+)CD25(+) (IL-2Ralpha) and memory CD4(+)CD127(+) (IL-7Ralpha) T cells, resulting in abrogation of carcinoma progression. Agonistic signaling through GITR, in the absence of NFATc2, thus emerges as a novel possible strategy for the treatment of human bronchial adenocarcinoma in the absence of NFATc2 by enhancing IL-2Ralpha(+) effector and IL-7Ralpha(+) memory-expressing T cells.