Cell growth assays using the xCELLigence system demonstrated that inducible lentiviral expression of MX2 (2–10-fold induction at 72 h; Supplementary Fig. 18a, b) resulted in slightly decreased growth of both melanoma cells and primary melanocytes at 100 ng/ml of doxycycline treatment, while empty vector transduced cells did not show any difference (Fig. 6b, c). This evidence concerns the gene MX2 and melanoma.