SCE and TM cells were plated in 35-mm culture dishes and grown to confluence. Total RNA was isolated (NucleoSpin RNA II; MACHEREY-NAGEL, Düren, Germany), and reverse-transcribed (RT) (Prime Script RT Master Mix; Takara Bio Inc., Shiga, Japan). The transcribed cDNA was amplified by polymerase chain reaction (PCR) (Platinum Taq DNA Polymerase High Fidelity; Invitrogen, Carlsbad, CA) according to the manufacturer's protocols. The gene-specific primer pairs were as follows: monkey CCR2: forward (F), 5′-CAT GCT GTC CAC ATC TCG TT-3′, reverse (R), 5′-TCA TTT GCA GCA GAG TGA GC-3′; monkey GAPDH: (F), 5′-ACC ACA GTC CAC GCC ATC AC-3′, (R), 5′-TCC ACC ACC CTG TTG CTG TA-3′; porcine CCR2: (F), 5′-TTG TGT GAC CCA AGA GAG ACT TACG-3′, (R), 5′-GTT ACA GCC AAA CCA TCC TAA AGC-3′; porcine GAPDH: (F), 5′-ACC ACA GTC CAT GCC ATC AC-3′, (R), 5′-TCC ACC ACC CTG TTG CTG TA-3′. The thermal cycling conditions were 94°C for 15 minutes (followed by 40 cycles of 94°C for 30 seconds, 60°C for 30 seconds, and 70°C for 30 seconds; then 70°C for 5 minutes). The PCR products were analyzed by electrophoresis using 1.5% agarose gels in 1× Tris base-boric acid-EDTA buffer containing ethidium bromide. To avoid the contamination of genomic DNA, the obtained total RNA samples were treated with DNase I and RT-PCR experiments without the use of reverse transcriptase enzyme were conducted.