Mineralized collagen and simple collagen matrices were implanted with 50,000 or 500,000 C4-2b cells and implanted subcutaneously into 4-week-old athymic mice. The tumor sizes from mice implanted with 500,000 C4-2b cells were compared at 2-weeks (a-b) (n=10, *p<0.01, versus collagen/tumor implant). The incidence of tumor formation was greater in mineralized compared to simple collagen implants in mice implanted with 50,000 C4-2b cells (c) (n=10, *p<0.01, versus collagen/tumor implant). (d) Representative images and quantitative results of of Ki-67 staining in regular and mineralized collagen/tumor sections. (n=8, * p<0.02).