Updated project metadata. The deubiquitinase USP9X related with multiple diseases including neurodegeneration, epilepsy and various type of tumor, by targeting different substrates. In our study, to deep study USP9X functional candidate substrates, we performed SILAC-based quantitative proteomic to compare knockdown USP9X with wild type HeLa cells to screen USP9X potential substrates. Further, we carried out Flag-NFX1-123 affinity tag-based interaction mass spectrometry method and verified that the X-box binding nuclear factor NFX1-123 is a substrate of USP9X. Further experimental evidences confirmed that USP9X stabilizedNFX1-123 protein level rather than mRNA levels via direct interaction and efficient deubiquitination of NFX1-123 protein