While none of the 6mer seeds present in the predominant arm (guide strand) of the most oncogenic miRNAs (miR-221/222, miR-21, miR-155, the miR-17~92, miR-106b~25, and miR-106a~36 clusters) were toxic (reduced viability >50%, stippled line in Fig. 4a), two of the major tumor-suppressive miRNA families, miR-15/16 and p53, regulated miR-34a/c and miR-34b contained toxic seeds in the guide strand (Fig. 4a). Here, TP53 is linked to neoplasm.