TCF21 and cholangiocarcinoma: We further observed that TCF21-overexpressing cells had higher levels of p-JNK (Figure 1C,D), which further confirmed the luciferase assay results in Figure 2B. In colorectal cancer [22] and cholangiocarcinoma [23], TCF21 functions as a tumor suppressor by modulating ERK and PI3K/Akt signaling.