The results suggest that enhanced E3 ligase activity of the core complex in A549/DDP cells might be responsible for cisplatin resistance, and the suppression of the core complex ligase activity and downregulation of FANCD2 monoubiquitnation by siRNA targeting FANCF or FANCL can reverse resistance of cisplatin-resistant lung cancer cells to cisplatin. The gene discussed is FANCD2; the disease is lung carcinoma.