Auteurs
Zhao T-Z, Zou S-P, Knapp PE (2007):
 
The authors exposed mouse neurons or astrocytes in primary cultures to a GSM cell phone at 1900 MHz for 2 hours. The opened phone was placed over an uncovered petri dish. Comparisons of gene levels in unexposed control cells were made with those seen with different modes of the phone i.e. "stand-by" and "on". Several genes were up-regulated in the neuron cultures in both stand-by and on modes. Several were also up-regulated in the astrocyte cultures, but only in the on mode.

The method of exposure in this experiment was very simplistic. No measures of SAR levels were made, and there does not even appear to have been any measurements of temperature in the experiment. The authors admit in their discussion that "the induction may result from thermal effects, non-thermal effects, or some combination thereof".