and seq id no 2 and the final 238 bases of the 3 u2032 utr fig3 and seq id no 3 all exhibited antiproliferative activity comparable to that of the full length 1 9 kb transcript the truncated antisense transcript and the 238 bases from the 5 u2032 end of the 852 base 3 u2032 utr both had little or no antiproliferative activity thus the antiproliferative activity mapped to the final 238 bases of the 3 u2032 utr indicating that mutation in this region leads to loss of antiproliferative activity antiproliferative activity of mutated prohibitin transcripts in hdfs and breast cancer cell lines antiproliferative activity of prohibitin rna corresponding to those isolated from three breast cancer cell lines bt 20 mcf7 and sk br 3 was performed according to the microinjection assay procedure given in example 4 the rna transcripts were produced according to the method given in jupe et al 1996 exp cell res 224 128 135 the mutated rnas corresponding to those from three breast cancer cell lines table i were unable to inhibit cell cycle progression in normal hdf fig7 even the single cytosine c 729 to thymine t 729 transition at utr 729 which represents an allelic polymorphism was sufficient to eliminate activity from the final 238 bases of the 3 u2032 utr in mcf7 however bt 20 which is mutated at two other.