Expression of stck^NIG.7954R under the control of Scer\GAL4^e22c leads to appearance of large misshapen multinucleate cells in the epidermis of third instar larvae (found predominantly but not exclusively near segmental borders) and mildly impairs epidermal wound closure. The segmental borders in the epidermis are ill-defined and the larvae show muscle fibers that had detached from the misaligned tendon cells forming the boundary, leading to locomotion defects. The nuclei in the syncytia are of normal size and only slightly reduced ploidy (less than 2-fold decrease), the syncytia do not activate either mitosis or apoptosis. Expression of stck^NIG.7954R under the control of Scer\GAL4^e22c also increases the number of nuclei in the central syncytium that forms around a puncture wound in the epidermis of third instar larvae.

One day pulse of stck^NIG.7954R RNAi expression during embryogenesis under the control of Scer\GAL4^pnr-MD237 and tub-Gal80[ts] (to limit the time of expression) results in syncytia formation at segmental boundaries and muscle detachment. A 2-day pulse leads to the syncytia spreading beyond the boundaries and the muscle detachment phenotype is worsened. 1 or 2-day pulse expression during the third instar larval stage or during embryogenesis but controlled by the Scer\GAL4^sr-md710 driver (expressing in the tendon cells) does not induce syncytia formation or muscle detachment. Continuous stck^NIG.7954R RNAi expression driven by Scer\GAL4^pnr-MD237 results in syncytia being formed both at boundaries as well as intrasegmentally, reflecting the gradual spatial restriction of the driver expression pattern.