CCR1 is a G protein-coupled chemokine receptor expressed on multiple leukocyte types that mediates immune cell migration and inflammatory responses 1. Upon activation by ligands including CCL3, CCL5-9, CCL13-16, and CCL23, CCR1 triggers intracellular signaling cascades that promote chemotaxis of monocytes, macrophages, T cells, dendritic cells, eosinophils, and neutrophils toward inflammatory sites 2. The receptor activates phospholipase C and ERK1/2 pathways, elevating cytosolic calcium and facilitating cell migration 3. In disease contexts, CCR1 drives pathological inflammation: it mediates eosinophil-derived CCL6-dependent allergic airway inflammation in asthma 2, promotes myeloid cell infiltration in pediatric high-grade gliomas 3, sustains pro-tumor neutrophil survival in hypoxic tumor microenvironments via CCL3 signaling 4, and facilitates aberrant B cell migration and diapedesis during EBV infection 5. Upregulation of CCR1 is associated with atherosclerosis pathology 6. Pharmacologic CCR1 antagonism shows therapeutic promise, extending survival in glioma-bearing mice and reducing allergic airway inflammation in asthma models 23, though clinical translation remains challenging 7.