I have been trying to use DMEM without amino acids + 10%FCS, but unfortunately I could not get any results. For colony formation assay, generally we seed around 300 cells per well, and after seeding them we change their mediums with amino acid starvation medium. How should I arrange timing for amino acid starvation? Should I leave the cells first in amino acid free medium and change with normal medium for last 3-4 days of colony formation assay as some papers show? Thank you very much for your response and time in advance.