animal tissue metabolism nonhuman 102 unclassified drug Animals 100 animal 96 controlled study 90 animal experiment 72 priority journal 64 Article 56 mouse 54 Mice 48 article 48 animal cell 43 messenger RNA 42 female 39 genetics 38 Female 35 physiology 35 animal model 33 male 31 protein expression 30 drug effects 28 Male 27 rat 27 gene expression 25 signal transduction 24 RNA, Messenger 23 gene expression regulation 22 Humans 21