In order to identify the factors that are associated with cancer-induced pain, we first examined the expression of several genes involved in the ephrin signalling pathway, including ephrin A1, ephrin A2, ephrin B1, ephrin B2, and the Eph A1 and Eph B1 receptors, in the DRGs of six-week old C57BL/6 mice injected with B16/BL6 melanoma cells into the plantar region of the right hind paw. This evidence concerns the gene EFNA1 and melanoma.