TCF7L1 and cancer: In addition, because TCF7L1 overexpression seems to have a paracrine effect on proliferation in vivo (Figure 2—figure supplement 1, Figure 4C) and that LCN2 is a secreted protein overexpressed in many types of cancer (Li and Chan, 2011), we surmise that TCF7L1 may drive tumor growth through induction of LCN2.