Non-repressed mRNA. Hairpin and stem loop structures form complementary sequences between the 5' cap and AUG codon, that can interfere with assembly and / or scanning of translation initiation. Further stabilization of the stem loop through RNA-binding proteins. Upstream AUG codons that are capable of causing premature initiation, thereby preventing the ribosome from reaching the true start site (Cazzola and Skoda, 2000).