Brits buy 17 illegal 'Barbie' tanning injections that 'lead to kidney failure, brain swelling and hallucinations' Retatrutide UK Research Grade Peptide 10mg 20mg 30mg A peptide that makes you tan. Sounds great. What could go wrong? When its activating your melanocytes to increase pigment in your skin, it may also be causing cancer melanoma. Ive had patients have Melanotan 2 (MT 2) is a synthetic peptide commonly studied for its role in melanin production and pigmentation processes. Researchers use it to explore skin response and peptide activity in controlled lab environments.