FBXW7 and non-small cell lung carcinoma: To identify the actual E3 ubiquitin ligase that mediates Topo IIα polyubiquitination and subsequent proteasomal degradation we focused on FBXW7, because Topo IIα was demonstrated to undergo GSK3-dependent and FBXW7-mediated proteasomal degradation (15), whereas osimertinib induces GSK3-dependent and FBXW7-mediated degradation of SREBP1 in EGFRm NSCLC cells, as we recently demonstrated (16).