Tyrosine phosphorylation is an important posttranslational modification used by various cells for regulating protein functions and signal transduction [1,2]. It is carried out by the PTKs (protein tyrosine kinases) while tyrosine dephosphorylation is carried out by PTPs (protein tyrosine phosphatases). PTPs include non-receptor-type PTPs and receptor-type PTPs (RPTPs), which play essential roles in regulating neurite outgrowth, axon guidance, and synaptic organization in developmental nervous system [2]. PTPσ, also known as LAR-PTP2, PTP-P1, CRYPσ, PTP-NU3, PTP-NE3 and CPTP1 is a RPTPs in the LAR subfamily. PTPσ has been researched for its physiological and pathological roles in the nervous system as it regulates synaptic plasticity in mature neurons and promotes neural growth. It also mediates axon regeneration by CSPG inhibition after CNS injuries. It also plays crucial roles for regulating immune responses as it is expressed in various immune cells such as pDCs, cDCs and CD4+ T cells and it can also regulate the development of autoimmune diseases [2].