PTPRC and plasma cell myeloma: For example, Lyn-deficient leukocytes, notably B cells, overproduce IL-6, and this establishes an inflammatory environment leading to the activation of B cells and cellular components, thus developing severe autoimmune pathology.8 In human multiple myeloma cells, the association of CD45 and Lyn requires the presence of IL-6.48 Nevertheless, how Lyn regulates IL-6- and IL-6-dependent signaling pathway is largely unknown.