Figure 1.

Determination of melanin in cell samples used in the experiments. EPR spectra of non-pigmented melanoma cells (A) and of pigmented melanoma cells with different levels of melanin pigmentation: moderately-pigmented (B) and heavily-pigmented (C) cells. The melanin EPR signal of pigmented cells is a superposition of pheomelanin signal (low field component) and eumelanin signal (high field component). Insets show images of cell pallets taken before freezing for EPR analysis. Note that the pellet of non-pigmented cells is white i.e. the cells are amelanotic, whereas the pellets of pigmented cells have a yellow-reddish color, which is typical for samples containing a mixture of pheomelanin and eumelanin.