Down-regulation of cathepsin gene expression in response to HIV-1 occurs in a dose-dependent manner. Day-6 MDDCs were treated with HIV-1_BaL at MOIs ranging from 50 to 0.1, or mock treated. After 48 hours, cathepsins B, C, S, and Z gene expression was determined by QPCR. All data were normalized to GAPDH expression. Representative data from 1 of 2 experiments are shown.