HNF4A and colorectal carcinoma: Another study, which included experiments on the effect of sulindac on TOPflash activity in human CRC cells, reported that treatment of SW620 human CRC cells with a very high concentration (1600 μM) of sulindac for 24 h was associated with increased ‘Tcf activity’ based on an increase in the TOPflash/FOPflash ratio (Bordonaro et al, 1999).