[Cell-biology] Lung fibroblast methotrexate toxicity

[Sonal Patel]

I am trying to find out effect of methotrexate on lung fibroblast WT cells
and KO where gene of my interest is knocked out . After 3 weeks on staining
with crystal violet I get lot of background cells in KO alongwith colonies.
Can anyone suggest me how to remove the background cells.