The Src homology region 2 (SH) domain-containing protein tyrosine phosphatase-1 (SHP-1) is a member of the large family of protein tyrosine phosphatase (PTP). SHP-1 was identified in hematopoietic cells and organs involved in immune responses such as the spleen, thymus, lymph node, and bone marrow. SHP-1 is also known as hematopoietic cell phosphatase (HCP) because of its expression in these cells. Herein the nomenclature SHP-1 will be used. Back to the beginning of the 1990s, the study of tyrosine kinases was very well advanced; however, knowledge about their natural counterpart the tyrosine phosphatases was still greatly unraveled. Early on, different research groups isolated and identified a protein that...