article metabolism priority journal unclassified drug nonhuman 82 controlled study 78 Animals 56 animal 56 genetics 55 Humans 41 human 41 physiology 40 animal cell 38 protein expression 35 chemistry 34 animal experiment 33 mouse 33 Mice 31 protein function 31 animal tissue 30 drug effect 28 enzymology 23 female 22 messenger RNA 22 Rats 21 enzyme activity 21 nucleotide sequence 21 rat 21 RNA, Messenger 20 gene expression regulation 20