CHRNA1 and glioblastoma: Furthermore, the expression of several AChRs was significantly elevated in the GBM samples including: CHRNA1, CHRNA9, and CHRNB1. The increased expression of CHRNA1 and CHRNB1 was surprising as these nicotinic subunits are generally considered part of “muscle” nicotinic receptors and their expression, to our knowledge, has not been characterized in the brain [54].