instruction:
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.
question:
Sentence1: Any antigen that causes an allergy is called an allergen. 
Sentence2: Antigens are proteins foreign to the body.
answer:
antigen


question:
Sentence1: Secondary accidents are a major problem under driving conditions of reduced visibility. 
Sentence2: Bad weather increases the risk of car accidents.
answer:
Secondary


question:
Sentence1: For example, the nuclear membrane keeps the DNA inside of the nucleus. 
Sentence2: RNA is a small molecule that can squeeze through pores of the nucleus that holds DNA.
answer:

DNA