CYP46A1 and glioblastoma: In the brain, when cholesterol acquisition exceeds functional needs, excretion occurs.[39] Conversion to oxysterol is the major outlet for cholesterol excretion and CYP46A1 is the main enzyme that converts cholesterol to 24-hydroxycholesterol (24-OHC).[40] Our data showed that CYP46A1 mRNA level was significantly lower in GBM than in LGG (Fig. 4).