NK cells from healthy donors display high phosphorylation of Vav1 upon CD16 but not NKp30 engagement. (A) Phosphorylation of Vav1 upon CD16 or NKp30 engagement in fresh NK cells. Vav1 was immunoprecipitated with polyclonal rabbit serum; phosphotyrosine was detected by mAb 4G10. Representative data of 1 of 3 experiments is shown. (B) Detection of total Vav1 protein. Blots were striped and reprobed with mAb to Vav1 protein. (C) Quantification of Vav1 phosphorylation. Densitometry of the bands was calculated to the relative specific phosphorylation without activation.