Studies using both melanoma cells and melanoma tumour-bearing mice by the group of Luigi Xodo have successfully shown that porphyrin C14H28-alkyl derivative C14, a photosensitiser identified as a G-quadruplex binding compound, induces growth arrest of cancer cells through downregulation of KRAS by targeting the G-quadruplex in its mRNA10,11. The gene discussed is KRAS; the disease is neoplasm.