You have a cell line that expresses a glucocorticoid receptor gene fused to a gf

You have a cell line that expresses a glucocorticoid receptor gene fused to a gfp gene. You accidentally left the cell line in the hood with the UV light on a few months back. You now see that upon the addition of dexamethasone it no longer localizes to the nucleus.
a) Where in the gene sequence would you suspect a possible mutation has occurred?
b) Suppose the defect resulted in localization of the glucocorticoid receptor to the nucleus and it bound DNA but there was no effect on gene expression. Where would you predict the mutation lie?