FN1 and urothelial carcinoma: This linkage is a requisite step for BCG's antitumor activity.[14] Rather than constituting a passive interaction, our prior reports have shown that FN mediated BCG adherence to the urothelial carcinoma surface has a pharmacogenetic effect as exemplified by transactivation of IL-6.[9] This effect is mediated through signal transduction pathways involving NF-κB and AP-1.