All mammals have three fibrillin genes (Davis & Summers 2012). Fibrillin-3 arose as a duplication of fibrillin-2 that did not occur in the rodent lineage. Fibrillin-1 is the major structural component of microfibrils (Kielty et al. 2005). Fibrillin-2 is expressed earlier in development than fibrillin-1 and may be important for elastic fiber formation (Zhang et al. 1994). Fibrillin-3 was isolated from and is predominantly expressed in brain; it is not known whether it forms microfibrils (Corson et al. 2004). Fibrillin-1 and -2 are degraded by MMP2, 9, 12 and 13 (Ashworth et al. 1999, Hindson et al. 1999). Fibrillin-1 is additionally degraded by MMP3 (Ashworth et al. 1999), the membrane-associated MMP14 (Ashworth et al. 1999), neutrophil elastase (ELANE) (Kielty et al. 1994), cathepsin L2 (V) and cathepsin K (Kirschner et al. 2011).