PTBP1 and central nervous system cancer: Only knock-down of PTBP1 lowered the ratio of ITSN1-S/ITSN1-L significantly by remarkably increasing ITSN1-L as well as slightly decreasing ITSN1-S, consistent with the results shown in U87MG and 140 (a primary glioma cell line) cell lines (Supplementary Fig. S1) as well as in LN229 cell line (Supplementary Fig. S2).