Incorporated into fibronectin-containing matrix fibers. May play a role in cell adhesion and migration along protein fibers within the extracellular matrix (ECM). Could be important for certain developmental processes and contribute to the supramolecular organization of ECM architecture, in particular to those of basement membranes. Has been implicated in a role in cellular transformation and tumor invasion, it appears to be a tumor suppressor. May play a role in haemostasis and thrombosis owing to its ability to bind fibrinogen and incorporate into clots. Could play a significant role in modulating the neurotrophic activities of APP, particularly soluble APP. Homomultimerizes and interacts with various extracellular matrix components such as FN1, LAMA1, LAMA2, NID, ACAN, CSPG2 and type IV collagen. Interacts also with APP and FGB. Interacts with FBLN7 (By similarity). Interacts with CCN3 (PubMed:9927660). (Microbial infection) Interacts with human papillomavirus/HPV type 16, 18 and 31 proteins E6. Isoform A and isoform B are only expressed in placenta. Isoform C and isoform D are expressed in a variety of tissues and cultured cells. Widely expressed during embryonic development. Prominent in the matrix of the leptomeningeal anlage, in basement membranes of the neuroepithelium and the perineurium of peripheral nerves. In embryos of gestational week (gw) 4, staining was observed in the early mesenchymal bone anlagen. In gw 6.5 and 8, all perichondrial structures showed expression but the chondrocytes themselves showed no staining. In gw 10, expression is prominent in the interterritorial matrix surrounding the hypertrophic chondrocytes. Expression increased by estrogen in ovarian cancer cells. A chromosomal aberration involving FBLN1 is found in a complex type of synpolydactyly referred to as 3/3-prime/4 synpolydactyly associated with metacarpal and metatarsal synostoses. Reciprocal translocation t(12;22)(p11.2;q13.3) with RASSF8. Fibroblasts derived from a patient with synpolydactyly displayed alterations in the level of isoform D splice variant incorporated into the ECM and secreted into the conditioned culture medium. By contrast, the expression of isoform C was not perturbed in the patients fibroblasts. Furthermore, no aberrant polypeptides were detected in extracts of cultured patients fibroblasts. The translocation t(12;22) may result in haploinsufficiency of the isoform D splice variant, which could lead to the observed limb malformation. Elevated expression and altered processing of FBLN1 protein is associated with human breast cancer. Belongs to the fibulin family.