mukB mutants of Escherichia coli are defective in the correct partitioning of replicated chromosomes. This results in the appearance of normal‐sized anucleate (chromosome‐less) cells during cell proliferation. Based on the nucleotide sequence of the mukB gene, the MukB protein of 177 kDa was predicted to be a filamentous protein with globular domains at the ends, and also having DNA binding and nucleotide binding abilities. Here we present evidence that the purified MukB protein possesses these characteristics. MukB forms a homodimer with a rod‐and‐hinge structure having a pair of large, C‐terminal globular domains at one end and a pair of small, N‐terminal globular domains at the opposite end; it tends to bend at a middle hinge site of the rod section. Chromatography in a DNA‐cellulose column and the gel retardation assay revealed that MukB possesses DNA binding activity. Photoaffinity cross‐linking experiments showed that MukB binds to ATP and GTP in the presence of Zn2+. Throughout the purification steps, acyl carrier protein was co‐purified with MukB.

Wnt signalling plays a critical role in the development of cancer. Recent studies indicate that Wnt signalling is negatively regulated by secreted Wnt antagonists such as secreted frizzled related proteins (sFRPs) and Dickkopfs (Dkks). We compared Dkk family expression levels in normal prostate and prostate cancer cells and found a reduction in Dkk-3 expression in cancer cells. Ectopic expression of Dkk-3 inhibited colony formation in LNCaP and PC3 prostate cancer cell lines and inducible expression of Dkk-3 reduced LNCaP cell proliferation. Moreover, small interfering RNAmediated downregulation of Dkk-3 enhanced cell cycle progression in untransformed RWPE-1 prostate epithelial cells. Immunohistochemical analysis revealed that Dkk-3 is expressed in a subset of normal prostate gland acini and that Dkk-3 expression is reduced in prostate tumours, particularly those with a high Gleason grade, suggesting a role for Dkk-3 in postmitotic differentiation. Consistent with this, depletion of Dkk-3 disrupted acinar morphogenesis of RWPE-1 cells in a threedimensional cell culture model. Our results are consistent with the loss of Dkk-3 expression resulting in impairment of glandular structure and uncontrolled prostate epithelial cell (PrEC) proliferation, both of which are crucial for prostate cancer progression.

The addition of diffusion-weighted images with a b-value of 2,000 s/mm2 to T2WI can improve the diagnostic performance of MR imaging in prostate cancer detection.

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