Getting the Index of a dataGridView Row in the MouseMove Event Window Application

private void dataGridView1_CellMouseMove(object sender, DataGridViewCellMouseEventArgs e)
  {
            if (e.RowIndex >= 0)
            {
                if (!((DataGridViewRow)(dataGridView1.Rows[e.RowIndex])).Selected)
                {
                    dataGridView1.ClearSelection();
                    ((DataGridViewRow)dataGridView1.Rows[e.RowIndex]).Selected = true;
                    if (dataGridView1.SelectedRows.Count > 0)
                    {
                       DataGridViewRow row = (DataGridViewRow)dataGridView1.Rows[e.RowIndex];
                        TextBox1.Text = e.RowIndex.ToString();
// return row index of dataGridView On CellMouseMove Event and Display RowIndex in TextBox1.                    }
                }
            }
        }