A Sensitive, Nondestructive Assay for Transfected Genes

Abstract
We have adapted the fibrin overlay assay for plasminogen activators (Jones et al., 1975) into a gene transfer expression assay which has the advantage of being very sensitive and nondestructive. In this assay plasminogen activators convert plasminogen to plasmin, which then degrades fibrin, resulting in clearings in a fibrin overlay. Furthermore, the assay can be used as a signal indicating the efficiency of gene transfer or the loss of introduced genetic elements in unstable cell lines.