This may seem obvious, but since it's part of the PMP Code of Professional Conduct, we'll mention it here. As a professional, you're required to follow all applicable laws and rules and regulations that apply to your industry, organization, or project. This includes PM1 organizational rules and policies as well. You should also follow any ethical standards and principles that may govern your industry or the state or country you're working in. Remember that rules or regulations you're used to in the United States may or may not apply to other countries and vice versa.
As a PMP, one of the responsibilities that falls into this category is the responsibility to report violations of the PMP code of conduct. In order to maintain integrity of the profession, PMPs must adhere to the code of conduct that makes all of us accountable to each other.
When you know a violation has occurred and you've verified the facts, notify PMI. Part of this process—and a requirement of the code of conduct—is that you'll comply with ethics violations and will assist PMI in the investigation by supplying information, confirming facts and dates, and so on. Violations include anything listed in the PMP Code of Professional Conduct, such as conflicts of interest, untruthful advertising and reporting of PMP experience and credentials, and so on, as well as appearances of impropriety. This one calls for some judgment on your part, but it's mostly based on common sense. For example, a PMP in most situations should not have a family member working on the project team reporting to them (unless they own and run a family business).