Generate an overlapping word between the given two sentences. When you find the overlapping words, they don't have to match exactly, e.g., "survival" and "survive" are valid overlapping words. Little words like "the" or "of" don't count! You must generate significant words which are not the stop words.
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Question: Sentence1: Protein Protein is needed for tissue maintenance and repair. 
Sentence2: protein repairs cells.

Answer: Protein


Question: Sentence1: Erosion of rock makes nutrients available. 
Sentence2: rain causes nutrients to be available.

Answer: nutrients


Question: Sentence1: Negative feedback controls insulin secretion by the pancreas. 
Sentence2: Insulin and glucagon are produced by the pancreas.

Answer:
pancreas