Serum deprivation enhances DNA synthesis of human hepatoma SMMC-7721 cells

Table 1 Ratios of the ³H-TdR incorporation among cells cultured in serum-free and different serum levels

Treatments	6 h	12 h	18 h	24 h
SF/2.5% FCS	2.47	1.63	0.778	1.67
SF/5% FCS	3.53	2.26	1.51	1.98
SF/10% FCS	7.34	3.35	2.19	3.27
SF/20% FCS	11.61	5.30	2.72	4.88
SF/25% FCS	39.32	7.21	3.53	7.35