Li et al. also found that, in CC containing transcriptionally active HPV-16, inactivation of tumour suppressor pathways occurs via degradation of the methylation of six key genes: MT1G, NMES1, RRAD, SFRP1, SPARC, and TFPI2; repression of viral oncogenes E6 and E7 restored tumour suppressor pathways and led to apoptosis [175]. This evidence concerns the gene SFRP1 and neoplasm.