Relative expression of the X-linked transgene. Sets of primers corresponding to fad2 or Gapdh were used for real-time RT-PCR analysis of the samples of transgenic or C57 kidney, brain, and liver. Expression data of fad2 were normalised to Gapdh expression and presented as the mean relative quantity (compared with X+X), with error bars representing the SEM. Student's t-test was used to calculate P values. Values with different superscripts were significantly different within same tissues (P < 0.05).