There is much debate over the practicality of using plants to produce proteins. Some groups fear that contamination of conventional crops might occur; in several instances, companies have been fined for violating protocols, resulting in potential contamination. This leads to the question of "Why would biotechnology companies use plants to produce proteins. Some groups fear that contamination of conventional crops might occur; in several instances, companies have been fined for violating protocols, resulting in potential contamination. This leads to the question of "Why would biotechnology companies use plants to produce proteins?" The first such drug manufactured from the milk of a mammal, such as a cow, sheep, or goat, is a common application, as milk production is plentiful and purification from milk is relatively easy. Hamsters and Rabbits have also been used in preliminary studies.