Animals nonhuman 80 breast cancer 70 Female 68 Mice 66 mouse 66 controlled study 62 article 60 female 60 Humans 54 human 54 priority journal 54 animal model 52 animal cell 48 animal experiment 48 Mice, Inbred BALB C 44 protein expression 44 Breast Neoplasms 36 animal 34 animal tissue 34 cell proliferation 34 progesterone receptor 34 Receptors, Progesterone 32 unclassified drug 32 human cell 30 metabolism 30 Mammary Neoplasms, Experimental 28 cancer growth 28 tumor growth 28 Cell Line, Tumor 26