Abstract
Synteny between fibronectin (FN) production and human chromosome 11 was established in cell hybrids of FN-producing embryonic diploid fibroblasts and non-producing heteroploid mouse A9 cells. Because the FN antiserum used reacts with both human and mouse FN, it is not clear if the human 11 carries structural or regulatory information for FN production or information that influences FN expression in some other way. In different human x mouse systems, Owerbach et al. (1978) found synteny between chromosome 8 and FN, and Smith et al. (1979) with 3 and 11. The latter authors suggest that chromosome 3 controls expression and that the 11 has the structural gene. The human 3 and 8 were eliminated as necessary for FN production in the hybrids of this study. Since different cell hybrids and FN assay methods were used in the three studies, and the species specificity of some of these assays has not been established, it is not clear if several structural FN loci, as well as regulatory or modifying factors, are involved. It will be interesting to clarify the mechanisms affecting the expression of this glycoprotein because it appears to play a role in differentiation, development, and possibly also in tumorigenicity.