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.

Example Input: Sentence1: Translation reads the genetic code in mRNA and makes a protein. 
Sentence2: Nucleotide sequences are read in mRNA and a protein is made.
Example Output: mRNA

Example Input: Sentence1: Mammals generate heat mainly by keeping their metabolic rate high. 
Sentence2: food keeps mammals' metabolic rates high.
Example Output: Mammals

Example Input: Sentence1: Flowers are the sex organs of certain plants and hold the male and female gamete producing systems. 
Sentence2: pollen consists of tiny grains that are held by flowers.
Example Output:
Flowers