Animals article controlled study nonhuman 2,236 priority journal 1,628 animal experiment 1,050 animal cell 1,042 Mice 868 mouse 806 animal tissue 772 Male 718 male 696 Female 688 female 672 unclassified drug 614 protein expression 562 Rats 558 animal model 544 rat 516 Humans 506 animal 428 human 410 Animalia 354 enzyme activity 328 metabolism 306 Rats, Sprague-Dawley 276 human cell 268 signal transduction 246 drug effect 244 in vitro study 236