(Adds cash withdrawals from equity mutual funds; quotes fromanalyst; table) By Sam Forgione NEW YORK, Sept 29 (Reuters) - Investors in U.S.-based fundspoured $2 billion into riskier high-yield junk bond funds in theweek ended Sept. 28, marking the biggest inflows into the fundssince mid-July, data from Thomson Reuters' Lipper service showedon Thursday. Stock funds attracted $622 million in inflows to mark theirfirst inflows since mid-August, while taxable bond funds overall