Using a human neuroblastoma cell line GOTO, the effects of delta 12-prostaglandin (PG) J2 on the modulation of cell cycle progression and protein synthesis were examined in comparison with those caused by heat shock (HS). delta 12-PGJ2 induced G1 arrest, the peak of which was obtained at 24 h and continued for 72 h. HS was found to induce G1 arrest earlier than delta 12-PGJ2. Furthermore, sequential HS could maintain G1 arrest. delta 12-PGJ2 induced the synthesis of several heat shock proteins (HSPs) in a manner similar to HS. Using immunoblot analysis, HSP72 was detected prior to inducing G1 arrest and accumulated during the subsequent 72h. The content of HSP72 induced by HS also correlated well with the induction, release, and maintenance of G1 arrest. In addition, both delta 12-PGJ2 and HS induced HSP72 mRNA and simultaneously suppressed N-myc mRNA expression. These results suggest that delta 12-PGJ2 and HS regulate cell cycle progression of GOTO cells via similar mechanisms.