Calling a subroutine from another user control

I have a user control on a master page. In that user control is a subroutine called DisplayGridView:
Protected Sub Page_Load(ByVal sender As Object, _
                          ByVal e As System.EventArgs) _
                          Handles Me.Load

    If Not Page.IsPostBack Then
      Call DisplayGridView()
    End If

  End Sub

  Protected Sub DisplayGridView()
  End Sub
On a page that references this master page, I have another GridView control, and in one column of this GridView I have another user control containing a button. When that button is clicked, I need to be able to execute DisplayGrid ...