The presence of Δ2-3 somatic transposase to Muller5-B X chromosome carrying five target P-elements causes pupal lethality, even without heat shock P{S-KP} can strongly repress the lethality. Combination of P{S-KP} and P{A-KP} can repress pupal lethality, repression is induced or enhanced by heat shock. P{S-KP} can repress gonadal dysgenesis through a zygotic effect with or without heat shock. P{S-KP} cannot repress snw mutability in the male germline or the somatic instability of snw (males have patches of weak sn, extreme sn and wild-type bristles) with or without heat shock. P{S-KP} has no effect on the expression of the Ecol\lacZ gene of P{lacZ}snunspecified or P{lacZ}vasunspecified.