That was because, if we used pcDNA3.1 plasmid only containing IGFBP7 gene, we could not estimate the transfection efficiency in-vivo experiments, and moreover, we could not discriminate whether high level of IGFBP7 expression in xenograft sections dued to plasmid transfection or physiological IGFBP7 synthesis of melanoma. Here, IGFBP7 is linked to melanoma.