Abstract
A FACS protocol is described that eliminates isolation and staining artifacts to allow accurate comparison between cell populations isolated from organs obtained from disparate mouse groups. This protocol was validated by characterizing the estrogen receptor positive cells within the mammary gland of transgenic mice with different genotypes at different stages of the estrous cycle. We include protocols necessary to batch stage animals within the cycle to proceed directly to FACS, which provides optimal RNA yields for RNA-seq. For complete details on the use and execution of this protocol, please refer to Ludwik et al. (2020).