However, findings from sarcoma and breast cancer models showed that lysyl hydroxylase 2 (LH2), which hydroxylates lysine (Lys) residues on collagen’s N- and C-terminal telopeptidyl domains prior to the initiation of cross-link formation by lysyl oxidase (LOX), promotes metastasis, is a target of hypoxia-inducible factor 1, and contributes to hypoxia-induced tumor stiffening7–9. Here, LOX is linked to breast cancer.