This animal study exposed 108 male Sprague-Dawley rats to 900 MHz EMF (1 mW/cm2) or sham for 14 or 28 days (3 h/day). The authors report that 28-day exposure was associated with impaired spatial memory, BBB permeability damage, and ultrastructural changes in hippocampus and cortex. They also report increased mkp-1 expression and ERK dephosphorylation, proposing activation of the mkp-1/ERK pathway as a mechanism.