VALIUM21, a variant of VALIUM22, differs only in that it lacks the ftz intron and gypsy sequences found in VALIUM22. VALIUM22 and VALIUM21 trigger effective RNAi knock-down and corresponding phenotypes in the female germline. The P-element transposase promoter is less effective than the hsp70 basal promoter in driving expression in somatic cells. Only 95 TRiP stocks have been generated in the VALIUM21 vector. --- See previous communication for description of VALIUM20 (FBrf0212437).