Western blot confirmation of MALDI-TOF identified serum proteins. A) Western blots were performed against pooled low (L) and high (H) abundance protein fractions for negative (lanes 2, 3), LTNP (lanes 4, 5), and HAART (lanes 6, 7) patients. Antibodies specific to cdk4, p16INK4A, PCTAIRE, HP1α, and HP1γ were used. B) Western blots were performed against individual patient samples 1-6, low and high abundant LTNPs. Antibodies specific to p16INK4A and cdk4 were used. 293T, the pooled low abundance LTNP samples "A," and the pooled high abundance LTNP samples "D" were used as controls. C) Immunoprecipitation of p16INK4A from the individual low abundant LTNP patient samples, followed by a western blot against p16INK4A. HeLa whole cell extract and the pooled low abundance LTNP sample "A" were used as controls.