PIK3CA and cancer: Our KTB normal breast RNAseq study supports this surprising albeit infrequent finding of expressed cancer gene hotspot mutations (Fig. 2, Supplement Table 2), and while we did not observe any difference in overall mutation burden or frequency between the Active and Inactive normal breast samples, further studies are needed to confirm our preliminary observations that normal breast mutation burden may correlate with adipocyte content and that Active samples may indeed possess more PIK3CA hotspot mutations.