The UK's most valuable monument is deemed to be the 1,000-year-old Tower of London, which is worth an estimated Â£56billion to the British economy and came it at number five in the list of European list. Its value is six times more than its nearest rival the Colosseum in Rome, which is valued at Â£72billion.
Cell cycle checkpoints are control mechanisms in eukaryotic cells which ensure proper division of the cell.
In order to continue with the cell cycle, two cyclins function in the G1 phase: cyclin D which functions in the middle of G1 and E which functions at the transition between G1 and S. Cyclin D1, cyclin D2, Cdk4, and Cdk6 are protoncogenes whose misexpression can cause inappropriate progression through this checkpoint.