. "Any process that stops, prevents or reduces the rate or extent of mRNA splicing via a spliceosomal mechanism." . . . . "negative regulation of mRNA splicing, via spliceosome" . "down regulation of nuclear mRNA splicing via U2-type spliceosome" . "down regulation of nuclear mRNA splicing, via spliceosome" . "down-regulation of nuclear mRNA splicing via U2-type spliceosome" . "down-regulation of nuclear mRNA splicing, via spliceosome" . "downregulation of nuclear mRNA splicing via U2-type spliceosome" . "downregulation of nuclear mRNA splicing, via spliceosome" . "inhibition of nuclear mRNA splicing via U2-type spliceosome" . "inhibition of nuclear mRNA splicing, via spliceosome" . "negative regulation of nuclear mRNA splicing via U2-type spliceosome" . "negative regulation of nuclear mRNA splicing, via spliceosome" . "negative regulation of pre-mRNA splicing" . . . .