Compare Cell Content in DataGridView

I have a data grid view that uses a data table as its data source.  I want to add an if statement condition in my code that ensures that all of the  cell values in Column2 are the same.  If they are not the same, I want to disable one of the radio buttons on the form.  So essentially I was looking for a string comparison statement that compared all the cells in Column2 to the value of the 1st row in Column2 using a foreach statement.  I would like to see an example.