Genes encoding acid phosphatase 5 (ACP5), a transport protein recently recognized as a prognostic biomarker in primary melanomas [22], and T-box 2 (TBX2), a transcription factor that is crucial in embryonic development and in suppressing senescence in melanoma [23], were also up-regulated in melanospheres (Fig. 4A). Here, TBX2 is linked to melanoma.