We observed enhanced expression of the activation markers CD69 and CD25 on T lymphocytes ex vivo in tumor-bearing LLA-TG-3 mice compared to tumor-free LLA-TG-3 mice mainly in non-draining LN, but also in spleens and tumor-draining LN for CD69+ CD4+ T cells, indicating a systemic immune response activation caused by tumor development. Here, CD69 is linked to neoplasm.