Unlike K562/cE cells, K562/D cells show no response to B3SAO coexpression.

These histograms illustrate the data listed in Table 4 for K562/D+B3SAO clone 2 (left column) and in Table 5 for K562/cE+B3SAO clone 3 (right column), which showed similar amounts of B3SAO expression. It should be kept in mind that the actual amount of B3SAO expressed at the cell surface is significantly underestimated by the BRIC 71 binding data (Table 3, and “Results”). In the histograms shown here, K562/D+pBn clone 2 and K562/cE+pBn clone 2 were used as negative controls. Coexpression of B3SAO in K562/D cells did not increase their affinity for BRIC 69 and only slightly increased their affinity for LA18.18. In contrast, coexpression in K562/cE cells increased their affinity for BRIC 69 approximately 3-fold and their affinity for LA18.18 approximately 4- to 5-fold. The small increase in LA18.18 binding displayed by K562/D+B3SAO clones may have been due to interactions of endogenously expressed CcEe–RhAG complexes with B3SAO (see “Discussion”).