Solved by a verified expert:Integrins are composed of a and b subunits that can pair up in numerous ways. The a7b1 integrin is the major integrin found in muscle, and mice that lack the a7 subunit develop muscular dystrophy. You just read a paper that found that injecting a synthetic peptide of the amino acid sequence RGD into the muscle of normal mice leads to muscle atrophy similar to that found in the a7 knockout mice. Explain why injection of RGD into muscle causes them to deteriorate and not contract as well.