Apply migrations and models from all the apps

I'm using Django and I have an schema like

mainapp
|---mainapp
|   |---migrations.py
|   |---models/
|---app2
    |---migrations/
    |---models/

But, when I execute:

python manage.py migrate it is generationg the tables of mainapp/models, but no the app2/models and app2/migrations either.

How can execute those migrations?