This CCDS representation uses the 5'-most in-frame start codon, which is conserved in higher primates, cow and dog. An alternative downstream start codon, which is more widely conserved and has a stronger Kozak signal, also exists. It is possible that leaky scanning by ribosomes would allow the downstream start codon to be used, at least some of the time. The use of the downstream start codon would result in a protein that is 26 aa shorter at the N-terminus. There is no experimental evidence showing which start codon is preferentially used in vivo.