Cyclopentenone prostaglandins (PGs), such as 15-deoxy-12,13-didehydro-14,15-didehydro-PGJ2 (15d-delta(12,14)-PDJ2), 12,13-didehydro-PGJ2 (delta12-PGJ2) and PGA2, are actively transported into cells and promote the expression of a variety of genes. The ultimate metabolite of PGD2, 15d-delta(12,14)-PGJ2, specifically binds to a nuclear receptor, the gamma isoform of the peroxisome proliferator-activated receptor, thereby promoting adipogenesis. Cyclopentenone PGs also induce the expression of various stress genes, such as heat shock proteins (HSPs), the immunoglobulin heavy chain binding protein (BiP) and protein disulfide isomerase by acting through heat shock element or unfolded protein response element. Overall, cyclopentenone PGs regulate cell growth, cell differentiation and stress responses by regulating various gene expression.