CHI3L1 and glioblastoma: An unbiased multiple-factor analysis (MFA; Methods), an extension of principal-component analysis (PCA) to multiple tables, showed that the largest contribution to variation in primary GBM neoplastic cells was an axis between MES (for example CD44 and CHI3L1) and PN (for example OLIG2 and DLL3) expression programs (Fig. 2a,b and Supplementary Tables 2 and 3).