The tumor volume of RM11 prostate tumors grown subcutaneously were significantly impeded (p < 0.04 and 0.02) in tumors grown in α11-KO mice compared to tumors grown in WT mice during their 13 day growth period, whereas 4T1 mammary tumors did not show any difference in tumor growth between α11-KO mice and WT mice when comparing tumors that were harvested on the same day (17 or 18) (Fig 2). The gene discussed is IGKV3D-20; the disease is breast cancer.