Cell signalling is regulated by two families of proteins, kinases and phosphatases; kinases attach a phosphate group to a protein, and phosphatases remove phosphate groups. Together, these two families of proteins regulate the most critical signalling pathways within cells. While these two families have been studied extensively in a myriad of contexts, currently we have not characterised fully the regulation of myeloid cell function by phosphatases. My current work focuses on the role of PTP1B in the regulation of dendritic cells during autoimmunity and cancer.