Lineage Tracing of Mammary Stem and Progenitor Cells.

Lineage tracing analysis allows mammary epithelial cells to be tracked in their natural environment, thereby revealing cell fate and proliferation choices in the intact tissue. This technique is particularly informative for studying how stem cells build and maintain the mammary epithelium during development and pregnancy. Here we describe two experimental systems based on Cre/loxP technology (CreERT2 /loxP and rtTA/tetO-Cre/loxP), which allow the inducible, permanent labeling of mammary epithelial cells following the administration of either tamoxifen or doxycycline.