Animals animal 123 human human cell metabolism Humans 111 controlled study 109 nonhuman 98 mouse 81 animal cell 75 Mice 73 unclassified drug 65 Article 60 priority journal 57 article 53 animal experiment 51 genetics 49 protein expression 48 chemistry 44 animal model 43 in vivo study 41 pathology 36 cell line 35 signal transduction 34 Cell Line 32 female 32 physiology 31 tumor cell line 31 drug effects 30 Cell Line, Tumor 29