Sequence alignment between 2k04(A) and UniProt seq P48061 (SDF1_HUMAN):

P48061 (SDF1_HUMAN): Stromal cell-derived factor 1 from Homo sapiens
                 10        20        30        40        50        60        70        80        90   
         ---------+---------+---------+---------+---------+---------+---------+---------+---------+---
UniProt: MNAKVVVVLVLVLTALCLSDGKPVSLSYRCPCRFFESHVARANVKHLKILNTPNCALQIVARLKNNNRQVCIDPKLKWIQEYLEKALNKRFKM
         ........................................................X............................X.......
PDB seq: ---------------------KPVSLSYRCPCRFFESHVARANVKHLKILNTPNCACQIVARLKNNNRQVCIDPKLKWIQEYLEKCLNK----
                              ---------+---------+---------+---------+---------+---------+--------    
                                      10        20        30        40        50        60