FIG. 4.

(A) Model for the synergy observed between Vav and Slp76. SH2 domains are indicated by closed boxes, SH3 domains are shown as dotted circles, the Vav DH domain is depicted as a shaded box, and the N-terminal domains of Slp76 are shown as an open box. PPPP, proline-rich region; P, phosphorylated tyrosine residues. (B) Possible points of functional interaction among the Vav, Ras, and Slp76 pathways. For simplicity, only one of the effector molecules of Rac (PAK) has been represented. The exact downstream elements of Vav leading to NF-AT activation have not been identified. The same applies to the pathways of Slp76 leading to ERK, PLC-γ1, and NF-AT activation.