From the given sentence, extract the phrase (often noun or verb) that carries the given relationship. The generated phrase should be present in the sentence.

Given Relationship: 'be professor of', Sentence: 'Your nerves learn to communicate more effectively with your muscle cells , allowing the muscle to recruit more cells during each contraction , says Mark A. W. Andrews , PhD , associate professor of physiology at Lake Erie College of Osteopathic Medicine in Erie , Pa .'
professor

Given Relationship: 'be son of', Sentence: 'And Gideon the son of Joash died4 in a good old age , and was buried11 in the sepulchre of Joash his father , in Ophrah of the Abiezrites .'
son

Given Relationship: 'open on', Sentence: 'Registration is now open for the forthcoming test administrations on January 21 and February 10 , 2007 .'

open