CD90.2 (Thy-1.2) is a 25-35 kDa glycosylphosphatidylinositol (GPI)-anchored membrane glycoprotein and a member of the immunoglobulin superfamily. It is primarily expressed on hematopoietic stem cells, neurons, all thymocytes, and peripheral T cells in mouse strains such as BALB/c, C57BL/6, and C3H. This molecule plays a role in cell adhesion, signal transduction, and the regulation of T cell activation. Additionally, CD90.2 is involved in lymphocyte proliferation and hematopoietic stem cell differentiation. It is also notable for its interaction with CD45 and its potential role in cell-cell interactions during synaptogenesis in the brain.