So we said that natural killer cells are part of the innate immunity because they destroy in a nonspecific way. They are not looking for any specific cell. They're looking for any abnormal cell, including cancer cells and infected cells. On the other hand, cytotoxic T cells are part of the adaptive immunity. And that's because they are looking for specific infected cells, which also includes cancer cells that contain specific foreign antigens on the membrane. So these cytotoxic T cells actually need the MHC class One to bind onto that infected or abnormal cell.