As I know Google doesn't care about PR. Last year, John Mueller from Google said "I wouldn't use PageRank or links as a metric. We've last updated PageRank more than a year ago (as far as I recall) and have no plans to do further updates. Think about what you want users to do on your site, and consider an appropriate metric for that." And still it isn't update yet. As I know last updated was on December 6, 2013. Basically, Google is careful about PR.