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: protein is used to repair cells by the human body. 
Sentence2: Wound healing requires protein.
[A]: protein


[Q]: Sentence1: Blood type is important for medical reasons. 
Sentence2: Type O is important for medical reasons.
[A]: important


[Q]: Sentence1: Solar UV radiation levels are highest during the middle of the day. 
Sentence2: Ozone depletion results in radiation levels that are highest during the middle of the day.
[A]:
day