CTSD and melanoma: On the bases of these results, we decided to contextually transfect either MM1 (Figure 5B) or MM4 (Figure 5C) cells, the two metastatic melanoma cell lines tested in in vivo experiments, with siRNA silencing cathepsin B, D and L. Forty-eight hours after transfection, we evaluated by flow cytometry: (i) the percentage of transfected cells (Figure 5B, MM1 cell line and Figure 5C, MM4 cell line) and (ii) the expression level of cathepsin B (second panel) cathepsin D (third panel) and cathepsin L (fourth panel).