Pleiotropic mutants of NIH 3T3 cells with altered regulation in the expression of both type I collagen and fibronectin.

Transformation of NIH 3T3 fibroblasts by v-mos causes a decrease in the levels of type I collagen RNA. In NIH 3T3 cells that have been made resistant to G418 by transfection with a plasmid in which the mouse alpha 2(I) collagen promoter is linked to the neo gene, subsequent v-mos transformation causes a loss of G418 resistance. After mutagenesis of these v-mos-transformed cells, G418-resistant colonies were selected. Two of these G418-resistant mutants showed an increased expression of the neo gene and of the endogenous type I collagen and fibronectin genes, without changes in their levels of v-mos RNA or in their ability to induce tumors. The mutations might alter cellular trans-acting factors that either directly or indirectly control the expression of the type I collagen and fibronectin genes in transformed cells.