There hasn't been any formal announcement about AP's withdrawal. On the USFSA INTERNATIONAL ASSIGNMENTS list, there is a note that AP withdrew from Cup of Russia due to injury.
(It's now the headline link from the USFSA home page.
"McDonough, who placed fourth at the 2003 Cup of China, has withdrawn from the Cup of Russia after suffering an injury at the Cup of China in Beijing. McDonough has a bruised right fibula and inflamed ligament. The injury, which happened the morning of the free skate, will keep her off the ice for five days.
"Mok has officially withdrawn form the NHK Trophy due to a continuation of a back injury that previously forced her to withdraw from Smart Ones Skate America in October."