To date, imidazolines have not been observed in RiPP natural products, but they are biosynthetically precedented; including alkaloids (e.g., spongotines,50 tulongicins,51 and penipanoid B52) and the siderophore, pseudochelin A (Figure S54).53 Perhaps the most well-known imidazoline compounds are the nutlins,54 anti-cancer compounds which inhibit the interaction of p53 and MDM2. This evidence concerns the gene MDM2 and cancer.