Figure 1.

Scheme describing the main signaling pathways activated by Zn²⁺ in the normal mammary gland cells. The Zn²⁺ transporters that play a role in mammary gland physiology and their localization are described in the figure. In particular, note ZnT2, that plays a role in vesicular Zn²⁺ accumulation during lactation and involution, and ZIP3/ZIP5, that were suggested to mediate Zn²⁺ influx. Arrows depict established pathways, while dotted lines and question marks are putative pathways that remain to be explored.