Alternative models of GSP-2 regulation of polarity establishment. Schematic representation of a one-cell stage embryo with anterior PAR proteins (in magenta) and posterior PAR proteins (in cyan). (A) PLK-1 (in pink) might downregulate, directly or indirectly, the activity of GSP-2 in the anterior of the embryo, contributing to inhibition of PAR-2 cortical localization. (B) At the anterior, PKC-3 phosphorylates PAR-2 and inhibits its cortical localization, whereas at the posterior, where there is no PKC-3 enrichment, dephosphorylation of PAR-2 by GSP-2 allows PAR-2 posterior cortical localization.