Used in research to study the melanocortin system, particularly the role of C-terminal ACTH fragments like ACTH(18-39), also known as CLIP (corticotropin-like intermediate lobe peptide). This fragment exhibits weak agonist activity at melanocortin receptors such as MC1R, MC3R, and MC4R, but minimal activity at MC2R. It is employed to investigate peptide-receptor interactions, binding affinities, and signaling pathways involved in inflammation, immune modulation, pigmentation, and energy homeostasis. Commonly applied in in vitro assays with cell cultures expressing melanocortin receptors to evaluate selectivity, antagonist properties, and downstream effects like cAMP production. Unlike full-length ACTH, it does not significantly stimulate adrenal steroidogenesis or cortisol secretion.