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.

Q: Sentence1: Mitosis is cell division. 
Sentence2: mitosis often causes growth.

A: Mitosis
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Q: Sentence1: Cells are the microscopic building blocks of organisms. 
Sentence2: proteins are the building blocks of organisms.

A: organisms
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Q: Sentence1: Like all plants, it needs sunlight and warmth to grow. 
Sentence2: If a tree falls, then sunlight becomes available to allow growth.

A:
grow
****