GridView.RowDataBound the last opportunity to access the data item

Before the GridView control can be rendered, each row in the control must be bound to a record in the data source. The RowDataBound event is raised when a data row (represented by a GridViewRow object) is bound to data in the GridView control. This enables you to provide an event-handling method that performs a custom routine, such as modifying the values of the data bound to the row, whenever this event occurs.

A GridViewRowEventArgs object is passed to the event-handling method, which enables you to access the properties of the row being bound. To access a specific cell in the row, use the Cells property of the GridViewRow object contained in the Row property of the GridViewRowEventArgs object. You can determine which row type (header row, data row, and so on) is being bound by using the RowType property.

void CustomersGridView_RowDataBound(Object sender, GridViewRowEventArgs e)
  {

    if(e.Row.RowType == DataControlRowType.DataRow)
    {
      // Display the company name in italics.
      e.Row.Cells[1].Text = "" + e.Row.Cells[1].Text + "";

    }

  }

Source:
http://msdn.microsoft.com/en-us/library/system.web.ui.webcontrols.gridview.rowdatabound.aspx