Multiple signaling pathways regulating steroidogenesis and steroidogenic acute regulatory protein expression: more complicated than we thought.

Steroid hormone biosynthesis in steroidogenic cells is regulated through trophic hormone activation of protein kinase A (PKA) signaling pathways. However, many examples of the regulation of steroid synthesis via pathways other than the PKA pathway have been documented. In some cases these pathways act independently of PKA activation whereas in other cases, they act synergistically with it. The current understanding of additional signaling pathways and factors, such as the protein kinase C pathway, arachidonic acid metabolites, growth factors, chloride ion, the calcium messenger system, and others capable of regulating/modulating steroid hormone biosynthesis, and in many cases steroidogenic acute regulatory protein expression, are discussed in this review.