TABLE 4.

The sy262 mutation displays very weak activity in the absence of functional EGFRs

Genotypea	% Suppression of let-23(null)-induced lethalityb	P valuec	% Suppression of let-23(null)-induced sterilityd	Vulval inductionf	% Muvh	% Vuli	nj	P valuek
let-23(null)	0 (1,091)		NAe	NAg	NAg	NAg	NAg
let-23(null); sy262	6 (1,372)	<0.001	0 (16)	0.98	0	91	11	0.013
let-23(null); let-60(gf)	100 (324)	<0.0001	0 (44)	5.73	100	0	11	<0.00001

^aThe complete genotype of let-23(null) was rol-6(e187) let-23(sy16); let-60(gf) = let-60(n1046gf); sy262 was linked to him-5(e1490).

^bSuppression of lethality was calculated from strains that were homozygous for the sy262 or let-60 mutation but heterozygous for the rol-6(e187) let-23(sy16) chromosome. In the absence of suppression, rolling adults never appear. In the presence of complete suppression, 25% of total descendants from the rol-6(e187) let-23(sy16) heterozygous parents would be rolling; 100% suppression is normalized to the generation of 25% rollers relative to total progeny. The number in parentheses refers to the total number of progeny examined from rol-6(e187) let-23(sy16) heterozygous parents.

^cThe statistical significance of the observed frequency of viable animals was determined by comparison with let-23(null) animals alone and using a chi square test.

^dAnimals suppressed for let-23(null)-induced lethality were picked as L4 larvae and examined for progeny 4 days later. The number in parentheses refers to the total number of animals examined.

^eNA, not applicable. Due to the 100% penetrant lethality conferred by the homozygous let-23(null) mutation, these animals could not be examined for sterility; 100% sterility, however, is inferred from reduction-of-function mutations in lin-3 and LET-23 structure-function studies.

^fAverage number of vulval progenitor cells adopting vulval fates. Wild type is three. The maximum is six.

^gNA, not applicable. Due to the 100% penetrant lethality conferred by the homozygous let-23(null) mutation, these animals could not be examined for vulval induction. However, based on certain combinations of let-23 alleles, it could be inferred that the vulval induction of these animals would be 0.00 and that 0% of the animals would be Muv.

^hPercentage of animals with more than three vulval progenitor cells adopting vulval fates.

ⁱPercentage of animals with fewer than three vulval progenitor cells adopting vulval fates.

^jn, number of animals examined for vulval induction.

^kThe statistical significance of the vulval induction value was determined by comparison with gonad-ablated wild-type animals and use of a two-tailed Student's t test.