PTPA and thymus lymphoma: Mechanistically, TCR‐mediated lymphocyte‐specific protein tyrosine kinase (LCK) activates RIPK3 to increase the phosphatase activity of protein phosphatase 2 (PP2A), preventing overactivation of extracellular signal‐regulated kinase (ERK) in DP thymocytes and limiting the progression of thymic lymphoma.