suppression of Ca2+ influx are as well a crucial event in the pathway to cell death. The present work on Jurkat cells significantly improves the knowledge concerning PPARa ligand toxicity on tumor-derived cell lines. So far, the data in the literature are relatively scanty and quite scattered in terms of cell types and drugs investigated, treatment schedule, and kinetic of the events under study. Two groups of neoplastic cell lines received the largest share of attention so far: those belonging to the hepatocytic lineage (see Introduction) and those of hematopoietic origin. Among the latter, evidence for growth arrest, induced differentiation and apoptosis driven by PPARa ligands, alone or combined with other drugs, has been obtained on neoplastic human cells of both lymphoid ([49], [50], [20]) and myeloid origin ([51,52,53,54], [55]). On this basis, we can at least conclude that remarkable antiblastic properties are exhibited by a variety of PPARa ligands. 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