Disruption of PiT1 in MEFs does not affect Na+-Pi cotransport but leads to reduced proliferation.

(A) MEFs proliferation curve. PiT1Δ5/Δ5 MEFs display a mean doubling time of 38 h, whereas PiT1+/+ and PiT1Δ5/+ MEFs had a growth rate of 18 h and 20 h, respectively. (B) Na+-Pi uptake in MEFs. Disruption of PiT1 in MEFs does not modify the overall Pi uptake. (C) Quantification of the expression of PiT1 and PiT2 mRNAs in PiT1+/+ and PiT1Δ5/Δ5 MEFs by real-time RT-PCR. Note the 1.8-fold overexpression of PiT2 mRNA in PiT1-null MEFs. * and # indicate significant differences as compared to wild-type controls with P<0.05 and P<0.001, respectively (Student's t test).