It was further demonstrated that high expression of PPARβ/δ in cancer cells is the most important factor for metastasis formation as heterozygous PPARβ/δ mice developed fewer metastases than their wildtype littermates; however, the most important metastasis inhibition was observed when PPARβ/δ was deleted in cancer cells used for syngenic tumor induction. The gene discussed is PPARD; the disease is neoplasm.