It is important to different cells to be able to make different proteins because that way they can perform they functions having the same gene code in a specific way. Multicellular organisms have different task for each structure and cell in their bodys, that's why cells specialize for the production of different proteins that are useful for their function, since a cardiac cell don't need the production of keratin for the operation of the heart muscles or a hair cell needs insulin to compose the hair fiber. Cells that are related to digestive or energetic functions normally produce proteins hormones or waxing proteins to carry out communication and meet metabolic needs, while epidermis cells needs proteins related to maintain the structure of the tissue.