Biochemical and Morphologic Properties of a New Lactating Mammary Tumor Line in the Rat.

acterization of the transplantable lactating mammary tumor R3230AB of the Fischer rat was recently reported (11). During that investigation, a slow growing variant neoplastic line occurred in 1 of the animals in which the mammary adenocarcinoma had been implanted for main tenance purposes. Examination of this subline revealed a mammary carcinoma which was comprised primarily of epithelial cells. Since the epithelial cells of the parent tumor were shown to respond to hormonal treatment, it was of interest to characterize further this subline, which we have called R3230AC. The approach for characterization of the R3230AC was