Seeing this question somewhere else, the sentence that supports such statement is "Human liver cells make proteins that promote homeostasis that neurons do not."
Being a complex, multicellular organism, it means that different cells within it will have different functions so that they can be specialised and work as a whole, all together, fulfilling all the needed functions for the sustaining of that organism's life. The fact that the liver cells, hepatocytes, are specialised in making proteins that neurons don't, and vice-versa, comes to justify exactly that.
