PTEN and invasive breast carcinoma: Using immunohistochemical staining of tissue microarrays, we have also studied the expression of PTEN (wild type) and its relationship with phosphorylated AKT, as well as with other recognized prognostic factors (HER-2 expression, oestrogen receptor status, histological grade, lymph node status at initial surgery, tumour size, age, menopausal status, risk of recurrence, and survival) in 429 cases of operable invasive breast cancer with a minimum 5 years of follow-up (Chan et al, 2003b).