Here, this approach was used to perform a complete experimental analysis of SLA-1*0401 and a limited analysis of the chimeric HPP and PHP molecules. A nonamer PSCPL analysis of SLA-1*0401 can be seen in Table 1 . AP values identified positions 9, 3, and 2 (in that order of importance) as the anchor positions of SLA-1*0401. In position 9, the amino acid preferences were dominated by the large and bulky aromatic tyrosine (Y), tryptophane (W), and phenylalanine (F), all having RB values above 4 (Table 1 ). In the almost equally important position 3, preferences for negatively charged amino acids glutamic acid (E) and aspartic acid (D) were observed. In the lesser important position 2, the most preferred amino acids were the hydrophobic amino acids valine (V), isoleucine (I), and leucine (L), followed by the polar amino acids threonine (T) and serine (S).