Figure 6.

Graded requirement for the spliceosome during the cell cycle. Schematic drawing of a dosage model to explain the varying cell cycle phenotypes caused by spliceosome inactivation. In this model, spliceosome is required for pre-mRNA splicing and subsequent expression of multiple proteins at all stages of the cell cycle. Depletion of spliceosome components results in cell cycle defects whose severity depends upon the efficiency of spliceosome depletion. Mild spliceosome depletion results in defects in the later stages of the cell cycle (e.g. mitosis or G2), whereas severe spliceosome depletion elicits a block in G1.