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.

Sentence1: Mammalian teeth are important for digestion. 
Sentence2: bats' teeth are important for digestion.
digestion

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

Sentence1: friction is used for stopping a vehicle by brakes. 
Sentence2: friction is used to stop a vehicle on an incline.

friction