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: Cell death occurs by activation of cell death genes. 
Sentence2: Aging is associated with the activation of certain genes.
activation

Sentence1: bacteria can cause people to become ill. 
Sentence2: bacteria can cause people to die.
bacteria

Sentence1: Some children drive their parents to distraction. 
Sentence2: Children can cause drivers to crash.

children