Overexpression of the N-terminal of mars (mars^{1-430.Scer\UAS.P\T.N.T:Avic\GFP}) during embryogenesis causes narrowing of spindle poles and fusion of mitotic spindles.

Overexpression of mars^{1-430.Scer\UAS.P\T.N.T:Avic\GFP} by maternally provided Scer\GAL4 (Scer\GAL4^{mat.αTub67C.T:Hsim\VP16}) causes embryonic lethality. Only 2.8% of embryos hatch as larvae. In individual mitotic spindles, three highly correlated major defects are observed. First, centrosomes often dissociate from mitotic spindles. The spindle poles remain sharply focused, even in cases where the centrosomes detach from the spindle. Second, the mitotic spindles without centrosomes tend to stack together instead of collapsing into monopolar spindles, as in mars⁹¹ mutants. Third, single chromosomes are found at the spindle poles while the remaining chromosomes are aligned at the metaphase plate. Chromosome segregation is also impaired in some cases, where chromosome bridges from in between the spindle poles at anaphase.

Overexpression of mars^{1-430.Scer\UAS.P\T.N.T:Avic\GFP} under the control of Scer\GAL4^da.G32 stabilises microtubules against the depolymerising drug demecolcine such that most of the mitotic spindles keep the poles focused and show a relatively even distribution of microtubules within the spindles.