Preparation of the samples

To expose NSCs to GSM 900-MHz RF-EMF, a known number of single cells from passage 2 neurospheres were resuspended in complete neurosphere medium supplemented with growth factors in 15-ml conical tubes. The tubes were centrifuged gently for 30 seconds to precipitate the cells to the bottom of the tubes. The tubes were placed circularly in the far field distance around the GSM antenna to obtain uniform irradiation for 0 (control), 15 (group A), 30 (group B), 60 (group C), and 120 (group D) minutes. The samples were kept inside a tissue culture incubator with 37℃ temperature and 95% humidity during the irradiation period.