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.

[EX Q]: Sentence1: For example, insulin is a protein hormone. 
Sentence2: Insulin is produced in a part of the cell called the ribosome.
[EX A]: insulin

[EX Q]: Sentence1: the ovaries are used in reproduction. 
Sentence2: Unlike most female animals, which have two functioning ovaries, the chicken usually has only one.
[EX A]: ovaries

[EX Q]: Sentence1: Lightning has long been the No. 1 cause of wildfires. 
Sentence2: Lightning can drastically change an ecosystem.
[EX A]:
Lightning