SIMS images of B16 melanoma cells from a mouse lung colony. A: CN- ions (m = 26) B: P- ions (m=31) – C: I- ions (m = 127), field 20 × 20 μm. As shown in figure 3, false colors allow the superimposition of the various ions. Iodine is strictly co-localized with melanin, which is essentially intracytoplasmic. The central cell is metaphasic and chromosomes can be seen in the pictures.