 The study investigates the role of extracellular signal-related kinases 1 to 2, YARC A1-2, and regulating the development of mouse primordial germ cells, PGCs, from 8.5 to 14.5 days post-codum, DPC. Using immunofluorescence and immunoblotting, the study found that YARC A1-2 was present in most proliferating PGCs at 8.5 to 10.5 DPC, low in 11.5 DPC PGCs, and progressively increasing between 12.5 to 14.5 DPC, both in female and male PGCs. In vitro culture experiments showed that inhibiting YARC A1-2 activation with the MEK-specific inhibitor U01-26 significantly reduced the growth of 8.5 DPC PGCs in culture, but had little effect on November 5 to December 5 DPC PGCs. The study also found that YARC A1-2 was necessary for maintaining the correct expression of oocyte-specific genes crucial for germ cells survival and the formation of primordial follicles. This article was authored by Maria Sorrenti, Francesca Joya Klinger, Severea Iona, and others.