USP4 and non-small cell lung carcinoma: We examined protein level of several de-ubiquitinases (USP4, USP40, USP7, USP8 and USP22) in six NSCLC cell lines and found USP40 was positively correlated with CFLARL (Fig. 1a and Additional file 1: Figure S1B) and GMEB1 (Fig. 1a and Additional file 1: Figure S1C).