Credit: UC San Diego School of Medicine
Mammary cells found during pregnancy that express integrin beta3 (CD61) act as stem cells, capable of reconstituting a new mammary gland in mice. This property may be to blame for the more aggressive nature of beta3-expressing breast cancer cells. Shown is a section from a mammary “outgrowth” harvested at lactation and immuno-stained for the epithelial markers E-cadherin (brown) and alpha-SMA (red).