void filter_function (GtkTreeView *treeview)
{
    GtkTreeModel *initial_model;
    GtkTreeModel *filter_model;

    initial_model= gtk_tree_view_get_model(GTK_TREE_VIEW( treeview )));
    filter_model = gtk_tree_model_filter_new( initial_model, NULL );

    gtk_tree_model_filter_set_visible_func (GTK_TREE_MODEL_FILTER ( filter_model ),(GtkTreeModelFilterVisibleFunc) filter_visible_func, NULL , NULL);

    /* Apply model */
    gtk_tree_view_set_model( GTK_TREE_VIEW( treeview ),filter_model);

    g_object_unref( filter_model );
    return;
}/* filter_function */

...

gboolean filter_visible_func (GtkTreeModel *model, GtkTreeIter *iter, gpointer data)
{
    gchar *expression = "SOMETHING";
    gchar *data;
    gchar *comp1;

    /* Get value from column */
    gtk_tree_model_get( GTK_TREE_MODEL(model), iter, COLUMN_X, &data, -1 );
    comp1 = g_utf8_strup (data, -1);

    if (g_strrstr(comp1, expression))
    {
        g_free (comp1);
        return TRUE;
    }
        else
    {
        g_free (comp1);
        return FALSE;
    }
}/* filter_visible_func*/