HMOX1 and neoplasm: Depletion of SPP results in inhibition of tumour proliferation and migration both in vitro and in vivo (Hsu et al., 2019; Liu et al., 2022), at least partially through impaired cleavage of the TA membrane protein heme oxygenase 1 (HO-1) and the type II membrane protein FKBP8 (Hsu et al., 2015).