Levels of the WT and mutant Gcn2 proteins were similar as judged by immunoblot analyses, and levels of Atf4 protein in this collection of Gcn2-expressing cells showed similar patterns of induction, with M802F and M802V cells showing pronounced increases in Atf4 protein levels even in the absence of HF treatment (Fig. 6C). This evidence concerns the gene EIF2AK4 and hydrops fetalis.