Immunoblot detection of PAL release from A. actinomycetemcomitans cells exposed to heat-inactivated FCS or cultured in broth. The samples were obtained from cell-culture wells outside the inserts, where the bacteria [D7SS (lane 1) and D7SS-p (lane 2)] or No bacteria (lane 3) were incubated in serum for 2 h and 8 h (Panel A) or cultured in broth for 24 h (Panel B). AaPAL was detected by immunoblot using anti-AaPAL peptide antiserum. Samples for bacterial culture and enumeration were taken from the inserts containing serum or broth (Panel C) at the same time points as the samples for the immunoblots in Panels A and B. The results show means (SD) from three independent experiments.