Though GPCR receptors may utilize Src-family kinases,126,131 they do not appear to be the predominant GPCR signal transduction molecules17 and Syk is not involved in GPCR signal transduction either.111 Though several studies suggest that Src-family kinases and Syk are critical for β2-integrin-mediated neutrophil activation,96,125,126 the fact that neutrophil activation is mediated by Mac-1 whereas K/BxN serum-transfer arthritis requires LFA-1115,123 suggests that this is not the case. Here, SYK is linked to Arthritis.