Recent characterization of the thrombin receptor indicates that it plays a role in T‐cell signalling pathways. However, little is known regarding the signalling events following stimulation of additional members of the protease‐activated receptor (PAR) family, i.e. PAR2 and PAR3. Most of the postligand cascades are largely unknown. Here, we illustrate that in Jurkat T‐leukaemic cells, activation of PAR1, PAR2 and PAR3 induce tyrosine phosphorylation of Vav1. This response was impaired in Jurkat T cells deficient in p56lck (JCaM1.6). Activation of PARs also led to an increase in tyrosine phosphorylation of ZAP‐70 and SLP‐76, two key proteins in T‐cell receptor (TCR) signalling. We also demonstrated that p56lck is meaningful for integrin signalling. Thus, JCaM1.6 cells exhibited a marked reduction in their adherence to fibronectin‐coated plates, as compared to the level of adherence of Jurkat T cells. While the phosphorylation of Vav1 in T cells is augmented following adhesion, no additional increase was noted following treatment of the adhered cells with PARs. Altogether, we have identified key components in the postligand‐signalling cascade of PARs and integrins. Furthermore, we have identified Lck as a critical and possibly upstream component of PAR‐induced Vav1 phosphorylation, as well as integrin activation, in Jurkat T cells.