Depends what you mean by prohormones. Technically, prohormones are those that have little or no anabolic/androgenic activity directly, but metabolize into anabolic/androgenic hormones/steroids. For example, 4-AD. (Which may or may not have direct AA activity, but metabolizes to testosterone which definitely has AA activity.) 19-NOR -> deca is another example.
Most of the products on the market since the '04 ban really aren't prohormones, and are more accurately called "designer steroids". For example, Superdrol, Pheraplex, etc. They don't metabolize into ("promote") other hormones; they have intrinsic AA activity in and of themselves. In actuality, these new "designer steroids" are more similar to old-school oral steroids than they are to the pre-ban prohormones. (In fact, many of these new designers actually are "old" compounds that just never got released commercially.)
Exceptions are products like prostanazol, which is a "prohormone" as it is metabolized into Winstrol.
Anyway, just thought this was worth noting. "Prohormone" is a confusing term, since it's often used to refer to any OTC anabolic supplement, regardless of whether the product is actually a prohormone/prosteroid or a true steroid.