Visual Basic.NET - Expresión regular detecta etiqueta html

Private Function QuitarEtiqueta(ByVal str As String) As String

        Dim RegExp As String = "<b[^>]*>[^<]*</b>"

        Dim R As New Regex(RegExp)

        Dim mc As MatchCollection = R.Matches(str)

        If mc.Count > 0 Then

            For Each m In mc

                Dim cadena = ((m.Result("$0").ToString))

                str = str.Replace(cadena, cadena.ToString.ToUpper)

            Next

        End If

        Return str

    End Function