The mRNA expression levels of monocytic chemokines, MIP-1 and MCP-1, in mock- and PCV2-inoculated porcine monocyte-derived macrophages (MDM). The mRNA expression levels of MIP-1 and MCP-1 and the corresponding housekeeping genes G3PDH and β-actin were analyzed at 0 and 24 h post-inoculation (HPI) by RT-PCR and gel electrophoresis. The results of gel electrophoresis of MIP-1 (A-1) and MCP-1 (A-2) at 24 HPI and corresponding G3PDH and β-actin are displayed. The mRNA expression levels of MIP-1 (B-1) and MCP-1 (B-2) were further normalized using the geometric mean of housekeeping genes G3PDH and β-actin and the values are expressed as relative levels of mRNA expression and shown as mean ± SD of three pigs from two independent experiments. *The difference between PCV2- and mock-inoculated groups is statistically significant (p < 0.05). Mock: MDM inoculated with an equal volume of RPMI-C; PCV2: MDM inoculated with PCV2 at an m.o.i. of 1. ■: mock-inoculated, □: PCV2-inoculated.