Nirenberg's genetic codon table. This chart from late 1965 or early 1966 lists the correspondence between genetic units called codons (down left) and amino acids (across top). This research was carried out by US biochemist Marshall Warren Nirenberg (1927-2010) and others at the US National Institutes of Health. By 1966, Nirenberg announced that he had deciphered the 64 RNA codons for all 20 amino acids. An example is alanine (ALA, first column) being identified with its codons GCU, GCC, GCA, and GCG (red box). Nirenberg shared the 1968 Nobel Prize in Physiology or Medicine for this work. See also image C025/9216.