PTEN and breast cancer: Four genes in the PI3K-Akt pathway, PIK3CA (55%, 38%, and 39% activated in benign CMT, malignant CMT and human breast cancer, respectively), PTEN (4%, 20%, and 13%), PIK3R1 (2%, 10%, and 8%), and AKT1 (0%, 9%, and 4%), showed comparable alteration frequencies between benign/malignant CMTs and human breast cancers, indicating that mutations in the PI3K-Akt signaling pathway are conserved across species in breast cancer pathogenesis.