We selected 11 genes belonging to various functional classes and frequently used as references in qRT-PCR gene expression experiments: β-actin (ACTB); tyrosine 3-monooxygenase/ tryptophan 5-monooxygenase activation protein, zeta polypeptide (YWHAZ); hypoxanthine phosphoribosyl-transferase I (HPRT); transferrin receptor (TFRC); succinate dehydrogenase complex, subunit A (SDHA); β-2-microglobulin (β2M); phosphoglycerate kinase I (PGK1); glyceraldehyde-3phosphate dehydrogenase (GAPDH); glucose-6-phosphate dehydrogenase (G6PD); ribosomal protein L19 (RPL19); and glycophorin C (GYPC). Specifically, GYPC was included into the panel because of its expression in the erythroid lineage and because it was used in a previous study as normalizer to quantify the expression of erythroid genes in sheep blood [11] .