RBX1 and neoplasm: Cells from the same tumors were also analyzed for the expressions of the SC and CSC marker aldehyde dehydrogenase (ALDH).[18] The silencing of RBX1 or FBXW8 significantly reduced the expression of ALDH in cells from the NUMB‐deficient tumor, but not in cells from the NUMB‐proficient one, further confirming that the degradation of NUMB, mediated by the CRL7FBXW8 complex, is needed for the maintenance of the CSC state (Figure S7, Supporting Information).