PIK3CA and breast cancer: In addition, re-analysis of available RNA-sequencing data of (n = 8) SF3B1 K700E mutant and stage, ER, PR, HER2, PIK3CA, and TP53 mutation status-matched SF3B1 wild-type breast cancers (n = 16) from TCGA revealed differential exon usage in 218 transcripts (p < 0.1 FDR, Supplementary Table 10).