private DataGridViewCell clickedCell;

private void dataGridView1_MouseDown(object sender, MouseEventArgs e)
{
// If the user right-clicks a cell, store it for use by the shortcut menu.
    if (e.Button == MouseButtons.Right)
    {
        DataGridView.HitTestInfo hit = dataGridView1.HitTest(e.X, e.Y);
        if (hit.Type == DataGridViewHitTestType.Cell)
        {
            clickedCell =
                dataGridView1.Rows[hit.RowIndex].Cells[hit.ColumnIndex];
        }
    }
}