ADCY9 and cancer: In the CHRNB4-high subgroup, CHRNB4 was co-expressed with numerous genes, such as ADCY9, NOTCH3, ARNT, NCOA1, and NCOA3, which correlated with multiple cancer-related processes [63,64,65,66,67], but only one gene, FLT4, was co-expressed in the CHRNB4-low subgroup [75].