Encodes a mutated form of msi with lesions within both the RRM-A region (amino acid replacements F218A, F220A and F223A) and in the RRM-B region (amino acid replacements F306A, F308A and F311A).
msiA.B fails to rescue msi1
Does not rescue either the msi1 mutant phenotype or the eye phenotype of double mutant of sina2/sina3 with msi1.