Angiogenesis is a critical process in the transition of tumors from a localized, primary site to a distant site of metastases. Hypoxic conditions within the tumor mass lead to the activation of signalling pathways which initiate tumor cell invasion, migration, adhesion and subsequent angiogenesis. Several key molecular players in hypoxia-induced tumor progression are well-described, e.g., hypoxia-inducible factor-1 (HIF-1) and angiopoietin-2; however, drug development aimed at suppressing individual members of this signalling cascade has proven to be challenging. The article by Erler et al. published in Nature (Vol. 440, April 2006) identifies lysyl oxidase (LOX) as an essential enzyme for hypoxia-induced metastases. This Journal Club reviews the findings presented by Erler and colleagues and briefly discusses the implications of LOX in cancer.