STAT5A and melanoma: Comparing increasing doses (6.25–200 nM) of compounds D and G in the cell-based assay, compound G was found to be more efficacious (EC50 = 20.9 nM) than compound D (EC50 >100 nM) and close to the unpegylated GGSSG-hGH-G120K (compound A, EC50 = 7.9 nM) in inhibiting hGH-induced STAT5 phosphorylation in human melanoma cells (Fig. 2E).