NBC Bay Area:  “A pair of San Francisco prominent medical marijuana businesses closed their doors Tuesday, a sign of the federal government’s recent crackdown on medical cannabis dispensaries.  HopeNet and the Vapor Room announced they would cease operations in response to threatening letters sent to the business’ landlords by the federal government.  ‘The Justice Department sent our landlord one of those nasty letters,’ said HopeNet co-founder Catherine Smith. ‘So this is our D-Day, we have to leave’. . . . Since November, the Justice Department has sent out 600 letters across California threatening landlords who rent space to medical marijuana operations.”