Studies on CD8+ T-cells have demonstrated that the absence of Shp1 allows cells to form more stable and longer-lasting synapses with antigen presenting cells (APCs) (95), leading to reduced T-cells activation thresholds and to the stimulation and proliferation of low-affinity T-cells; this causes an increased number of tumor specific effector T-cells and a more efficient control of tumor growth (96, 97). The gene discussed is PTPN6; the disease is neoplasm.