While melatonin, up to 2.0 mM, has no cytotoxic effects, it intriguingly suppresses cellular motility, migration, and invasion in human osteosarcoma U2OS and HOS cells and represses the gene expression of C-C motif chemokine ligand 24 (CCL24) in U2OS cells [45]. The gene discussed is CCL24; the disease is osteosarcoma.