In the column labeled "TACI short" in Figure 6A on page 1756, the lower cell in the image in the bottom row is incorrect; it is the same as the upper cell in the image in the second row of the same column. The corrected Figure 6 is shown below. The authors apologize for the error, which does not change the conclusions of the experiment. The error has been corrected in the online version of the article. (Figure Presented).