Retroviral mediated over-expression of SOCS1 and SOCS3. GFP expression was evaluated by flow cytometry in melanoma cells stably transduced with PINCO retroviral vectors over-expressing SOCS1 or SOCS3. A representative example is shown in (a). Over-expression of (b) SOCS1 and (c) SOCS3 at the protein level was confirmed by immunoblot analysis. Membranes were stripped and re-probed with β-actin as a control for equal loading.