Bioelectromagnetics 27:578 ^ 588 (2006) Radiofrequency Radiation Does Not Induce Stress Response in HumanT-Lymphocytes and Rat Primary Astrocytes Jae-Seon Lee, 1{ Tai-Qin Huang, 1 Tae-Hyung Kim, 1 Jin Young Kim, 2 Hyun Jeong Kim, 2 Jeong-Ki Pack, 3 and Jeong-Sun Seo 1 * 1 Department of Biochemistry and Molecular Biology, ILCHUN Molecular Medicine Institute MRC, Seoul National University College of Medicine, Seoul, Korea 2 Department of Dental Anesthesiology and Dental Research Institute, Seoul National University College of Dentistry, Seoul, Korea 3 Department of Radio Sciences & Engineering, Chungnam National University, Daejeon, Korea Heat shock proteins (HSPs) are rapidly induced by a variety of stressors, including heat shock, ethanol, heavy metals, UV, and g-radiation. Mitogen-activated protein kinases (MAPKs) are also involved in the stress transduction pathways in all eukaryotes. In this study, we attempted to determine whether radiofrequency (RF) radiation is able to induce a non-thermal stress response. Human T-lymphocyte Jurkat cells and rat primary astrocytes were exposed to 1763 MHz of RF radiation at an average specific absorption rate (SAR) of either 2 W/kg or 20 W/kg, for 30 min or 1 h. Temperature was completely controlled at 37  0.2 8C throughout the exposure period. The sham exposures were performed under exactly identical experimental conditions without exposure to RF radiation. We assessed alterations in the expression of HSPs and the activation of MAPKs in the RF-exposed cells. No detectable difference was observed in the expression levels of HSP90, HSP70, and HSP27. The phosphorylation status of MAPKs, extracellular signal-regulated kinases (ERK1/2), c-Jun N-terminal protein kinases (JNK1/2), or p38, did not change significantly. In order to determine whether RF radiation can promote the effects of 12-O-tetradecanoylphorbol 13-acetate (TPA) on stress response, cells were exposed to RF radiation coupled with TPA treatment. When TPA alone was applied, the MAPKs were found to be phosphorylated in a dose-dependent manner. However, RF radiation did not result in any enhancement of TPA-induced MAPK phosphorylation. Neither TPA nor RF radiation exerted any detectable effect on the induction of HSPs. These results indicate that 1763 MHz RF radiation alone did not elicit any stress response, nor did it have any effect on TPA-induced MAPK phosphorylation, under our experimental conditions. Bioelectromagnetics 27:578–588, 2006. ß 2006 Wiley-Liss, Inc. Key words: RF radiation; mobile phone; HSP; MAPK INTRODUCTION The use of mobile phones has increased contin- uously over recent years, and the mobile phone has become one of the principal sources of environmental radiofrequency (RF) radiation. A number of studies have been performed in order to determine whether RF radiation triggers stress responses [Cleary et al., 1997; Fritze et al., 1997; Leszczynski et al., 2002]. Although some available evidence suggests that RF radiation induces stress responses, many contradictory findings have also been reported; and the available evidence on both sides appears equally compelling. Therefore, further research will be required in order to determine whether RF radiation could be an environmental stressor. ß 2006 Wiley-Liss, Inc. —————— Grant sponsor: The Ministry of Information and Communication of Korea; Grant number: 2003-X-004. { Jae-Seon Lee’s present address is Laboratory of Functional Genomics, Korean Institute of Radiological & Medical Sciences, Seoul, Korea. *Correspondence to: Jeong-Sun Seo, ILCHUN Molecular Med- icine Institute MRC, Seoul National University College of Medicine, Seoul 110-799, Korea. E-mail: jeongsun@snu.ac.kr Received for review 1 July 2005; Final revision received 17 February 2006 DOI 10.1002/bem.20235 Published online 12 July 2006 in Wiley InterScience (www.interscience.wiley.com).