Fibulins area family of ECM glycoproteins characterized by a fibulin-type C-terminal domain preceded by tandem calcium-binding epidermal growth factor (EGF)-like modules. They are involved in protein-protein interaction with the components of basement membrane and extracellular matrix proteins. There are five fibulins, which can be classified into two subgroups. Fibulin-1 and -2 constitute one subgroup. These fibulins are larger than the others due to the presence of a higher number of EGF modules and an extra domain with three anaphylatoxin modules []. Members of the second subgroup, fibulin-3, -4, and -5, are similarly small in size and highly homologous to one another in modular structure. They consist of a modified cbEGF domain at the N terminus followed by five tandem cbEGF modules and the fibulin-type C-terminal region.EGF-containing fibulin-like extracellular matrix protein 1 (EFEMP1, also known as Fibulin-3) binds EGFR, the EGF receptor, inducing EGFR autophosphorylation and the activation of downstream signalling pathways []. It promotes glioma growth and resistance through a novel paracrine regulation of Notch signalling []and may function as a negative regulator of chondrocyte differentiation [].
