California Code, Corporations Code - CORP § 13404

A corporation may be formed under the General Corporation Law or pursuant to subdivision (b) of Section 13406 for the purposes of qualifying as a professional corporation in the manner provided in this part and rendering professional services. The articles of incorporation of a professional corporation shall contain a specific statement that the corporation is a professional corporation within the meaning of this part. Except as provided in subdivision (b) of Section 13401, no professional corporation shall render professional services in this state without a currently effective certificate of registration issued by the governmental agency regulating the profession in which such corporation is or proposes to be engaged, pursuant to the applicable provisions of the Business and Professions Code or the Chiropractic Act expressly authorizing such professional services to be rendered by a professional corporation.