MMP9 and melanoma: Nevertheless these possibilities have been questioned since: a) Bcl-2 down-regulation in 518A2 melanoma cells did not associate with down-regulation of MMP-2 or MMP-9; and b) also in 518A2 tumor cells, transfected with the Bcl-2 plasmid and growing as xenografts, extensive necrosis in the setting of very poor vascularity was observed [10].