PTEN and triple-negative breast carcinoma: Loss of phosphatase and tensin homolog (PTEN) expression has been reported in 37 to 74% of metastatic triple-negative breast cancers[14-16], which results in activation of the PI3K/PTEN/AKT/mTOR pathway, making mTOR inhibitors also a potential molecular target for treating TNBC[17,18].