An example is VEGF,52 which acts directly to promote new blood vessel growth, and secretion of TNF-α and IL-1α, which act indirectly to drive the secretion of pro-angiogenic factors by melanoma cells.53 Aside from angiogenesis, macrophages promote melanoma progression, as evidenced by their increased density at the invasive front of melanoma lesions,54,55 and promote metastasis. Here, TNF is linked to melanoma.