['Neuroblastoma is a common pediatric tumor of the sympathetic nervous system. Unlike the ones found in older children, the tumors found in patients younger than one year of age often show spontaneous differentiation and regression. Peroxisome proliferator-activated receptor gamma (PPAR-gamma), a member of the nuclear hormone receptor superfamily is expressed in several human cancers. Recently, PPAR-gamma has been reported to be expressed in neuroblastoma, and the agonist of this receptor caused differentiation of neuroblastoma cells.', 'In this report we studied the expression of PPAR-gamma mRNA, using LightCycler in neuroblastoma samples diagnosed in 17 patients under the age of one year.', 'Twelve samples showed PPAR-gamma mRNA expression. There was no significant difference in the PPAR-gamma mRNA expression based on age, histology, staging, and DNA ploidy. The PPAR-gamma mRNA expression level was significantly correlated with the change in urinary vanillyl mandelic acid (VMA). The neuroblastoma samples resected from patients who showed a decrease in their urinary VMA before the operation showed significantly higher PPAR-gamma expression than those from patients who showed an increase in their urinary VMA before the operation.'] Is expression of PPAR-gamma correlated with the clinical course of neuroblastoma?