Mich. Comp. Laws § 38.2603
Except as provided in this act, a retirement board member or employee of the retirement board shall not have any interest, direct or indirect, in the gains or profits of any investments made of retirement system funds. Except as provided in section 202, a board member shall not, directly or indirectly, receive any pay for his or her services. A board member or person connected with the retirement board directly or indirectly, for himself or herself or as an agent or partner of others, shall not borrow any of the retirement system funds or deposits, or in any manner use retirement system funds except to make current and necessary payments that are authorized by the retirement board. A board member or employee of the retirement board shall not become an endorser of surety or become in any manner an obligor for money loaned by or borrowed from the retirement board.
MCL 38.2603