The liver has the greatest capacity for regeneration amongst human organs - but there's always room for improvement. Here, cancer researchers incidentally uncover a potential mechanism to safely boost regenerative capacity: "During chronic liver damage repetitive waves of hepatocyte cell death and compensatory proliferation take place, eventually culminating in chronic liver failure and often in the development of hepatocellular carcinoma (HCC). A misregulated regenerative response to chronic liver injury may represent the base for development of HCC. Therefore, a more detailed understanding of signaling pathways involved in proliferation control of hepatocytes not only holds the great promise of informing new therapies to increase the hepatic regenerative potential but also to deduce new strategies for the treatment of HCC. We have established a unique system to perform in vivo RNAi screens to genetically dissect cellular signaling networks regulating hepatocyte proliferation during chronic liver damage. ... we identified shRNAs which showed strong enrichment during regeneration, therefore pinpointing new regulators of liver regeneration. Our top scoring candidate represents a kinase, which is accessible to pharmacological inhibition. Functional in vivo validation studies show that stable knockdown of the candidate gene by different shRNAs can significantly increase the repopulation efficiency of mouse hepatocytes and also increases the regenerative capacity of chronically damaged mouse livers. Despite the fact that some human HCCs show focal deletion of the candidate gene, a therapeutic window for regenerative therapy exists, as mice stably repopulated with shRNAs against the candidate did not develop liver tumors."