ENG and invasive breast carcinoma: However, in this study, between one and two-thirds of the vessels within pre-malignant, preinvasive and invasive breast cancers exhibited proliferating ECs (based on CCS calculated with CD31 and endoglin staining) in contrast to a report by Wang et al (1994), which showed that endoglin stained only 20% of the vessels highlighted by CD31 in invasive breast carcinomas.