US STOCKS-Wall St opens lower as Greek crisis weighs
* Greece talks suffer setback after IMF quits
* May producer prices record biggest gain in more than 2-1/2 years
* Apple weighs on Nasdaq; IBM on Dow
* Twitter rises after CEO quits
* Indexes down: Dow 0.7 pct, S&P 0.6 pct, Nasdaq 0.5 pct (Updates to open)
By Tanya Agrawal
June 12 (Reuters) - U.S. stocks opened weaker on Friday, pressured by a setback in Greek debt talks and increased chances of a rate hike in September as a recovery in the U.S. economy gathers steam.
Greece said it would not cross its "red lines" as it looked to intensify political negotiations for an agreement, saying IMF's move to quit bailout talks was aimed at putting pressure on Athens.
Investors were also edgy ahead of the U.S. Federal Reserve's Open Market Committee meeting next week, the central bank's last meeting before September, which may provide clues regarding the timing of an interest rate hike. Continuación...