Cdx4 expression was increased by HoxA10 overexpression and decreased by HoxA10 knockdown in U937 myeloid leukemia cells. A, HoxA10 expression level influenced Cdx4 mRNA abundance in a dose-dependent manner. U937 cells were stably transfected with a vector to overexpress HoxA10 or Cdx4 (or empty expression vector) and a vector to express HoxA10-specific shRNAs, Cdx4-specific shRNAs, or scrambled shRNA controls. Expression of HoxA10 and Cdx4 mRNA was determined by real-time PCR. * and **, statistically significant differences in HoxA10 expression with HoxA10 overexpression or knockdown, respectively (p < 0.00001, n = 6). *** and #, statistically significant differences in HoxA10 expression with Cdx4 overexpression (p < 0.02, n = 6). ##, significant increase in HoxA10 expression in shCdx4-expressing cells with HoxA10 overexpression (p < 0.0001, n = 6). ### and &, significant differences in Cdx4 expression in cells with HoxA10 overexpression or knockdown (p < 0.0001, n = 6). && and &&&, significant increase in Cdx4 expression with Cdx4 overexpression (p < 0.0001, n = 6). +, significant increase in Cdx4 expression in cells with shHoxA10 upon Cdx4 overexpression (p < 0.0001, n = 6). B, HoxA10 expression level influenced Cdx4 protein abundance. U937 cells were stably co-transfected with a vector to overexpress HoxA10 or Cdx4 (or empty expression vector) and with a vector to express HoxA10-specific shRNAs or bp-swapping, scrambled shRNAs. Total cell lysates were separated by SDS-PAGE, and Western blots were serially probed with antibodies to Cdx4, HoxA10, and tubulin (as a loading control). C, HoxA10 overexpression partly rescued Cdx4 protein expression in cells with Cdx4 knockdown. U937 cells were stably co-transfected with a vector to overexpress HoxA10 (or expression vector control) and a vector to express Cdx4-specific shRNAs or scrambled shRNAs. Total cell lysates were separated by SDS-PAGE, and Western blots were serially probed with antibodies to Cdx4, HoxA10, and GAPDH (as a loading control). Error bars, S.E.