Vav1 is involved in NFAT activation in more that one pathway in T cells. A scheme of the cardinal regulatory pathways in which Vav1 is involved as an organizer of the cytoskeleton and a regulator of Ca²⁺ flux, thus leading to NFAT activation, is depicted. (A) This scheme depicts the initial steps in TCR activation and tyrosine kinase stimulation. (B) Tyrosine phosphorylation of Vav1 and other signaling proteins leads to association between these proteins and their activation. (C) Following TCR stimulation and activation of additional proteins, Vav1 activates Rac and is involved in Ca² release as well as Ras activation. (D) A summary scheme of the various pathways in which Vav1 is involved in T cells that culminate in NFAT activation. A detailed explanation for each pathway is included in “Vav1 induces Ca²⁺ release: potential signaling cascades.”