Figure 5. Theoretical relationship between the proportion PhH3/MIB-1 and T_i (cell cycle interphase duration) showing decoupled cell cycle phase duration phenomenon among different tumors: as T_i increases the proportion PhH3/MIB-1 diminishes.

When for instance S phase duration increases in aneuploid tumors, MIB-1 count will be proportionally larger than PhH3 as compared to another tumor with the same MIB-1 count but with a shorter S phase duration. This effect would explain “imperfect” correlation between PhH3 (or mitotic count) versus MIB-1. Also because of lengthened S phase two tumors with identical mitotic count could have different MIB-1 fractions.