MUP1 is a subfamily of proteins found in abundance in the urine and other secretions of many animals. It provides a small range of identifying information about the donor animal, when detected by the vomeronasal organ of the receiving animal. It can also act as protein pheromones themselves. It has been demonstrated to promote aggression in male mice, and one specific Mup protein found in male mouse urine is sexually attractive to female mice. Recombinant mouse MUP1 protein, fused to His-tag at N-terminus, was expressed in E.coli and purified by using conventional chromatography.