Figure 3

Growth of HMECs infected with the ERα virus is dependent on oestrogen. (a) Immunofluorescent staining for oestrogen receptor alpha (ERα) and Ki-67 of human mammary epithelial cells (HMECs) grown in the presence of oestrogen. HMECs infected with the ERα and BMI1 viruses together are Ki-67-positive, whereas HMECs infected with the ERα virus alone are Ki-67-negative. (b) Growth curves of HMECs expressing the indicated transgenes in the presence of oestradiol (E) or fulvestrant (F). The left and right panels show HMEC strains from two different patients. ERα and BMI1 are necessary for proliferation; transduction with MYC leads to a further increase in proliferation (right panel). Proliferation is increased by oestrogen and blocked by fulvestrant. The grey curves, labelled EtOH in the left panel, show the behaviour of cells in the absence of exogenous oestrogen or fulvestrant.