GATA3 and neoplasm: Given the present results showing that GATA3 is phosphorylated in serine 308 during cell cycle progression (Figure 4C) and that impairment of such phosphorylation prevents GATA3 downregulation by MPA (Figure 4F), we next investigated the association between GATA3 downregulation and progestin-induced in vitro proliferation and in vivo tumor growth.