The cell line KYSE-150R displayed significant radioresistance compared to the parental cell line KYSE-150. (A) the growth curve of KYSE-150R cells and the parental cells. (B) Clonogenic survival assays of KYSE-150R group and control group. Surviving fractions were calculated by the number of colonies divided by the number of seeded cells multiplied by plating efficiency. (C) The KYSE-150R cells were morphologically distinct from the parental cell lines.