Recent studies have shown that activation of platelets by collagen is mediated through the
same pathway as that used by immune receptors, with pivotal roles for an immunoreceptor
tyrosine-based activation motif (ITAM) sequence on the Fc receptor γ-chain and the tyrosine
kinase Syk. Here, Steve Watson and Jonathan Gibbins discuss the implications for the
physiological and pathological regulation of blood platelets.