SOX2 and melanoma: We do find, however, that the injected mouse melanoma TRCs proliferate better than control melanoma cells at the primary site and are more efficient in forming micrometastasis and metastatic colonization at the secondary sites, which is highly dependent on Sox2 expression, leading to tumor size expansion from 2 dpf to 5 dpf (0 dpi to 3 dpi, Figs 3 and 5), consistent with published results in mice12, 13.