Sos-1-dependent activation of Rac1. (A) PAE carrying human Tie-2 were transfected with Sos-1-DH or vector alone and cell lysates were immunoblotted with an anti-Sos-1 (Santa Cruz Biotechnology) Ab. The lower and higher bands correspond to Sos-1 and Sos-1-DH, respectively.³⁴  (B). Pull-down assay of Rac1 from starved and subconfluent cells stimulated for the indicated times with Ang-1 (50 ng/mL). Densitometric analysis evaluated as in Figure 4 is shown (mean ± SD of 3 independent experiments; ^*P < .05 versus unstimulated cells by t test).