OPRK1 and myeloid sarcoma: Our laboratory recentlydemonstrated that the synthetic cyclotide T20K, derived from kalataB1 (isolated from Oldenlandia affinis), a Möbius-typecyclotide (Table S1, Supporting Information), decreases clinical symptoms in the EAE model of MS following oraladministration.19 Knowing that (i) caripecyclotides activate KOR, (ii) T20K is a clinical candidate for thetreatment for MS,20 and (iii) the KOR wasidentified as a therapeutic target in MS models,29−31 we interrogatedwhether T20K could modulate KOR signaling as well.