HMOX1 and cancer: In this regard, HO‐1 inhibition with ZnPPIX in Mφ also resulted in the reduction of the CD163 protein level (Figure 3I), a common marker of tumor‐promoting and antiinflammatory macrophages, whose expression by TAMs and cancer cells has been shown to be a strong indicator of poor prognosis in several human cancers, including gliomas.49, 50