CD8⁺ T cells from LGLL patients maintain constitutively activated ERK1/2 and PI3K. CD8⁺ T-cell lysates were prepared from LGLL patients and healthy donors. The activity of ERK and PI3K in these cells was assessed by Western blot analyses using antibodies specific for (A) phosphorylated ERK1/2 (pERK) and (C) phosphorylated AKT. Membranes were stripped and reprobed with antibodies that detect (B) pan-ERK and (D) pan-AKT to demonstrate total protein levels.