Animals article controlled study nonhuman 2,100 priority journal 1,527 animal experiment 998 animal cell 965 Mice 796 mouse 739 animal tissue 736 Male 675 Female 655 male 655 female 640 unclassified drug 569 Rats 529 protein expression 518 animal model 516 rat 491 Humans 467 animal 388 human 383 Animalia 333 enzyme activity 314 metabolism 275 Rats, Sprague-Dawley 269 human cell 249 drug effect 230 in vitro study 222 signal transduction 221