Serializer Dealing with nested objects

Using the Django REST framework I have the following Serializer below. I would like to add in (nested) related objects (ProductCatSerializer) to ProductSerializer. I have tried the following....

class ProductCatSerializer(serializers.ModelSerializer):
    class Meta:
        model = ProductCat
        fields = ('id', 'title')

class ProductSerializer(serializers.ModelSerializer):
    """
    Serializing the Product instances into representations.
    """
    ProductCat = ProductCatSerializer()

    class Meta:
        model = Product
        fields = ('id', 'title', 'description', 'price',)

So what I want to happen is Products to show its related category nested in the results.

Thank you.

Update:

Using the depth = 2 option (thanks Nandeep Mali ) I now get the nested values, but they only show using ID's and not keyparis like the rest of the json request (see category below). Its almost right.

"results": [
        {
            "id": 1, 
            "title": "test ", 
            "description": "test", 
            "price": "2.99", 
            "product_url": "222", 
            "product_ref": "222", 
            "active": true, 
            "created": "2013-02-15T15:49:28Z", 
            "modified": "2013-02-17T13:05:28Z", 
            "category": [
                1, 
                2
            ],