PTEN and thyroid tumor: Notably, when we divided the tumors into two groups based on PTEN gene expression status (PTEN_high and PTEN_low, compared with the average of its expression in normal tissue), to mimic the loss of PTEN as has been reported in thyroid tumors (Bruni et al. 2000, Gimm et al. 2000), we found significant reduction in SDHC and SDHD transcript expression in the PTEN_low group compared with the PTEN_high group (P<0.001 and P=0.02 respectively, Fig. 3B).