PIK3CA mRNA expression in breast carcinoma tissue was significantly higher than in normal breast tissue (p = 2 × 10-11), with a median value of 56 for the PIK3CA/HMBS ratio in breast carcinoma tissue compared to 23 PIK3CA/HMBS in normal breast tissue (Figure 2) PIK3CA mRNA expression was increased in tumour tissue in 114 out of 149 patients (76%). The gene discussed is PIK3CA; the disease is breast carcinoma.