Figure 1

Relationship between culture days and population doubling level (PDL). Colon adenocarcinoma cells (LoVo and DLD-1) were continuously passaged in the culture medium containing 0.5 μg/ml of CDDP and 1 × 10-7 M of 5-FU. (Clear square): control cells (without anti-cancer drugs); (Black diamond): cells cultured with anti-cancer drugs (CDDP + 5-FU). The arrows indicate 4, 15, 39 PDL in LoVo cells and 7, 27, 58 PDL in DLD-1 cells, respectively.