PTBP1 and glioblastoma: However, three splice factors could be linked to GBM-specific splicing events having p < 0.05 (see Additional file 9): A2BP1 regulates CLTB, GRIN1, MAG, NF1 and SCN8A splicing, PTB regulates CLTB, GABA, GRIN and FGFR2 splicing, and CUGBP2 regulates RASGRF1 splicing [32-35].