SPP1 and neoplasm: For example, the products of CYR61 (also known as CCN1) and CYTL1 stimulate, and lumican (encoded by LUM) inhibits, angiogenesis in tumor, skin pouch, and in vitro assays41–44; NDP acting via Fz4/Lrp receptors regulates retinal vascularization45; and SSP1 codes for the cytokine osteopontin, which is required for post-ischemic neovascularization in a femoral artery ligation model46.