The weakest link A new paradigm for stabilizing the integrin-actin connection

recently shown to lack catalytic activity. 3-5 Interestingly, the pseudo-active catalytic site of ILK binds another adaptor, termed parvin, in a manner resembling a kinase– substrate interaction. 4 Parvins exist in 3 isoforms in vertebrates and are characterized by 2 in-tandem arranged calponin homology (CH) domains that constitute an actin-binding domain. The second CH domain also mediates the interaction with ILK and targets the complex to FAs, providing a direct link between integrins and the actin cytoskeleton. Consequently, ILK-deficient fibroblasts display a severe delay in the formation of FAs. Once established, the FAs are smaller in size and poorly linked to a disorganized actin cytoskeleton, highlighting the importance of ILK in regulating actin engagement downstream of integrins. 3 The integrin–actin linkage, although