We use to use FBS form Gibco to culture our colon cance cell lines (HCT-116, COLO-205, HT-29 and SW-620) and it were o.k, with good morphological appearance as in the database, I sub-cultured them every 2-3 days. But recently we started using FBS from another company, but we realize the cell's growth are very low, we subculture them every 8-10 days, and even the morphological forms have changed. So could change of FBS (Fetal Bovine Serum) affect the quality of the cell?