Host MMP13 knockout does not alter mammary tumor size. E0771 mouse mammary tumor cells were implanted into the mammary fat pad of congenic female C57BL/6 WT or MMP13 KO mice as described in Methods. Tumors were measured with calipers at days 12, 19, and 28 post-implantation, and tumor volume calculated. There was no difference in tumor volume between WT and MMP13 KO mice at any of the time points, indicating that MMP13 knockout does not alter E0771 mouse mammary tumor size. Plot represents mean tumor volumes ± SEM from a cohort of WT (blue) (n=6) and MMP13 KO (red) (n=4) mice.