KIT and intrahepatic cholangiocarcinoma: The protein level of SK3 (KCNN3), which encodes Ca2+-activated K channels and is highly expressed in colonic PDGFRα+ cells, showed a decreased expression in the proximal colons of PW3 and an increased expression in the proximal and distal colon of PW5 (Figure 2C).The mRNA levels of c-Kit, the signature gene of ICC, were also markedly elevated in the proximal colon of PW3 and PW5 mice (Figure 2D,E) but the mRNA of c-Kit exhibited no changes in the expression in the distal colon up to PW5 (Figure 2D).