SFRP1 and osteogenesis imperfecta: Most importantly, however, whereas the expression of molecular markers for osteoblast differentiation or of genes mutated in other types of OI were not affected by WNT1/SFRP1 administration, there was a striking induction of two genes encoding extracellular matrix modifiers, i.e., Postn and Omd. The strong WNT1-mediated induction of these genes was also confirmed in transfected ST2 cells, and here, the Wnt1G177C mutation fully abrogated this response.