HMOX1 and central nervous system cancer: Considering its involvement in type 2 helper T (Th2) activation, immunomodulation, and tumor progression, combined with the fact that Th2/Th1 ratio is a poor prognostic marker in gliomas (Kumar et al., 2006), we have good reasons to believe that HMOX1 is involved in immunoregulation in glioma microenvironment, driving tumors toward more malignant properties as well as a worse prognosis.