Melanin production is highly variable across melanocyte lineages.

<p>a) Melanin production varied significantly between cell lineages at baseline (<i>p</i><0.0001) and in response to fibroblast-conditioned medium (<i>p</i> = 0.01); the magnitude of response to fibroblast-conditioned medium varied significantly across samples (<i>p</i> = 0.03). Melanin production was not consistent with either reported race or pigmentation type as assigned by Life Technologies. Statistical analysis was based on average values across all six samples rather than individual sample responses to fibroblast-conditioned medium (see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0139135#sec006" target="_blank">Methods</a>). b) Photodocumentation of cell pellets from each of the melanocyte cell lineages demonstrated no dramatic differences in melanin appearance.