animal cell nonhuman controlled study 222 Article 209 animal experiment 167 mouse 145 Animals 143 animal 134 male 125 animal tissue 121 animal model 100 human 91 unclassified drug 86 female 82 metabolism 76 Mice 66 Humans 65 rat 61 protein expression 58 in vitro study 55 adult 48 Male 46 gene expression 46 human cell 46 genetics 42 in vivo study 41 drug effect 40 article 39 priority journal 37 Rats 34