SFRP1 and lip and oral cavity carcinoma: Relevant studies of OSCC that evaluated the expression level of SFRP1 showed that it was dramatically down-regulated in tumor samples compared to control ones (p < 0.001, n = 32 versus n = 329, 3.67 ± 2.10 versus 5.91 ± 1.57), which suggested a role for SFRP1 as a suppressor in oral cancer (Figure 2b,c).