two assays were used to demonstrate that these new v-ki-ras integrations were generated by superinfection with a `` '' helper '' '' retrovirus , not sarcomagenic by itself in the nude mice , that led to rescue/reinfection of tumor cells with the defective kirsten sarcoma proviral genome -- cellular transformation of 3t3 or c3h10t1/2 cells and rna dot blot analyses for medium-secreted retrovirus specific for ltr or v-ki-ras sequences .
C0007634
2 cel
C1327616
m-secret