In GBM, USP5 isoform2 was closely associated with the aberrant expression of polypyrimidine tract-binding protein 1 (PTBP1), an RNA splicing factor in GBM, and the forced expression of USP5 isoform1 inhibited cell growth and migration in two GBM cell lines, implying an essential role of individual USP5 isoforms generated by alternative splicing in gliomagenesis49. This evidence concerns the gene PTBP1 and glioblastoma.