Model for chromokinesin function in chromosome congression. The left-hand side of the scheme depicts the proposed functions of hKID and KIF4A. On aligned chromosomes, hKID stabilizes the orientation of chromosome arms and by generating PEF that pushes the spindle poles apart. KIF4A limits the elongation of MTs near chromatin and could thereby control the number of MT plus-ends interacting with chromosomes or with MTs from the opposite pole (sliding interpolar MTs). Via MT cross-linking proteins MT-dependent forces are distributed throughout the spindle, which is required for regular chromosome oscillations. Reduced kinetochore MT flux after loss of KIF4A could either be due to changes in the dynamics of MTs interacting with chromosome arms or could be caused by a tighter binding of MTs to kinetochores due to kinetochore stretching (yellow symbols). In combination with loss of hKID, this results in chromosome attachment, congression, and segregation failures.