ALK and astrocytoma (excluding glioblastoma): ALK (5A4) immunopositivity (IHC score≧1) was evident in 9 (17.6%) of 51 GII, 5 (17.2%) of 29 GIII, and 29 (49.2%) of 52 GIV (GBM) astrocytomas, and the IHC scores were significantly higher in GBM as compared to those of GII and GIII tumors (Fig 1B).