COL18A1 and renal cell carcinoma: To determine the extent to which p53 activation regulates the deposition of endostatin and arresten in the ECM of RCC, mice bearing xenografts generated from 786-0 stably transfected with a tetracycline-regulable p53 shRNA (see Methods) were treated with sunitinib with or without the inclusion of doxycycline in the drinking water.