ERBB4 and glioblastoma: However, significantly more CYT-2 than CYT-1 was expressed in NNB (p = 0.004; Figure 2G) and GBM (p = 0.006; Figure 2H), indicating that CYT-2 is the predominant cytoplasmic ERBB4 variant in the brain (NNB and GBM).