Reaching undetectable on HAART lessens your risk of transmitting HIV, but not to zero -- even for women [see "Vagina Monologues," POZ, October 2001]. Case in point: UCSF's Lesley Benet, MD, reports that during the two weeks between ovulation and menstruation, HIVers on protease inhibitors (PIs) see their drug's effectiveness plummet -- at least in their vagina. Why? Look at levels of p-glycoprotein (p-GP), which spike at this time of the month. That protein pumps PIs out of infected cells, upping the chance of viral breakthrough. "This may have important treatment implications," Benet says darkly. But until we learn just what, my protease pretties, keep pill-popping and rubbering-up.