animal cell human nonhuman unclassified drug Animals 172 controlled study 172 Humans 162 human cell 150 article 142 priority journal 120 mouse 112 Mice 102 animal 90 protein expression 86 metabolism 78 Cell Line 56 animal experiment 56 female 52 Article 48 animal model 48 Cercopithecus aethiops 44 chemistry 40 cell line 38 protein function 38 Female 36 genetics 36 in vitro study 36 drug effects 34 in vivo study 34 signal transduction 34