The STR DNA profile can determine if there is no contamination or alteration of the cultured cell line as compared to the original cells. The results may be able to identify a contaminant and also measure instability or other changes in the cell line. There are several mathematical measures that can assist in the probability of a match when compared to the reference cell line (see previous question/answer for reference to ANSI/ATCC ASN-0002 guidance document).