SOST and melanoma: In parallel, we observed that the pro-osteogenic-differentiating medium induces a stronger positivity for the Alizarin Red staining in acid-adapted melanoma cells compared with control cells, despite at a molecular level only ALPL (for A375M6 and M21 cells) and SOST (for M21 cells) genes were significantly increased in acidic-adapted cells (Fig. 6c).