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Molecular Cell Biology

The Homebody RNA

Why does some RNA stay in the nucleus rather than rushing off to make proteins? 

PYK2 (red) and the cell-surface receptor (green) that triggers the cellular transition to a pro-metastatic state are found in the same membrane compartment (yellow) from which the transition signal is transmitted

A signal stuck in the “on” position may hasten metastasis in certain breast cancers

Cultured colorectal cancer cells. Top: Cells that have become resistant to certain forms of chemotherapy and continue to thrive. Bottom: The same cells, which have had the LIP gene inserted and are then treated with chemotherapy drugs

What makes cancer cells survive chemotherapy?

Normal human colonic crypts. SMOC-2 expression (red) in the colonic stem cells demonstrates that these cells are localized in the bottoms of the crypts. Bars represent 100 micrometers (left) and 50 micrometers (right)

Some tumor cells in the advanced stages of colorectal cancer adopt a...

A melanoma cancer cell is labeled with invadopodia markers in fluorescence microscopy

How does a cancer cell push its way out of the surrounding tissue?

cytoskeleton structure

The growth of cellular “skeletons” reveals a clear directional pattern

Activity of a glucose-manufacturing gene in mouse liver tissue, viewed under a fluorescence microscope. A high concentration of mRNA (red dots) reveals that this activity is highest near a blood vessel (PP) that bathes the tissue in oxygen-rich blood, essential for glucose manufacture

Fits and spurts of gene expression help the liver cope with change

Paradox Alice in Wonderland

Why do biological systems use the same signaling molecule for opposite purposes?

(l-r) Dr. Ariel Livne, Prof. Benjamin Geiger and Dr. Eran Bouchbiner

To understand how cells orient themselves, Weizmann Institute researchers turned to a model from physics

Cytoskeletal fibers (green) and adhesion sites (orange) grow when the Arp2/3 complex is present in its hybrid version (right) compared with the regular, seven-subunit version (left). When Arp2/3 is absent altogether, the fibers and the adhesion sites deteriorate (center)

A seven-unit structure that helps a cell move can rearrange to help anchor it in place