Department of Anatomy and Structural Biology, Albert Einstein College of Medicine of Yeshiva University, 1300 Morris Park Avenue, Bronx, New York 10461, USA.
We report a technique to evaluate the same tumor microenvironment over multiple intravital imaging sessions in living mice. We optically marked individual tumor cells expressing photoswitchable proteins in an orthotopic mammary carcinoma and followed them for extended periods through a mammary imaging window. We found that two distinct microenvironments in the same orthotopic mammary tumor affected differently the invasion and intravasation of tumor cells.