Primary human foreskin fibroblasts at passages 15-18, cultured in Eagles Minimal Essential Medium (MEM) supplemented with penicillin and 10% fetal calf serum (FCS). Confluent cells serum starved for 3 days with MEM containing 1% FCS. 85% of cells in G0/G1 phase of cell cycle. mRNA was isolated using a direct mRNA extraction kit. Keywords = fibroblast, cultured, cell cycle synchronized