ERBB4 and glioblastoma: Additionally, the JM-c (non-cleavable) and JM-d (cleavable) mRNA levels were significantly lower than the JM-a and JM-b mRNA levels found in GBM and NNB; however, the JM-c and JM-d mRNA levels were significantly higher in GBM than NNB (p = 0.04 and p = 0.04, respectively) (Figure S2A,B), indicating that an increase in rare ERBB4 variants is associated with GBM.