Introduction

Much of our basic knowledge concerning plasma proteins and their purification derives from work in the 1940s in the laboratory of Cohn at Harvard Medical School, where a group of talented investigators concentrated, for the first time, on the systematic fractionation of plasma [1]. Not surprisingly, plasma fibronectin was also identified by this group in a paper published by Edsall and colleagues in 1948 [2]. At first called cold-insoluble globulin because coprecipitation with fibrinogen was a major characteristic of the protein, plasma fibronectin did not appear to have any discernible function, nor did it attract much research interest. For some time there was little interest in the structure or function of this cold-insoluble globulin, and some investigators were not certain that it was a unique plasma protein. However, in 1968, Mosesson 2et al. discovered a patient with cryofibrinogenemia, in which the "cryofibrinogen" contained both fibrinogen and cold-insoluble globulin [3]. This observation led Mosesson and colleagues to purify the protein and to study its physical and chemical characteristics [4,5], These studies clearly established cold-insoluble globulin as a unique plasma protein, present in significant concentration. However, it was as yet a plasma protein with no obvious function.