GAPDH and colorectal carcinoma: Interestingly, following serum starvation for 24 to 72 h, BDNF mRNA levels (Figure 2A), as well as mature BDNF protein (17 kDa) detected by Western blot in cell lysates, were enhanced in the four CRC cells (Figure 2B), as shown by densitometry values (BDNF/GAPDH ratios for mRNA and BDNF/Actin ratios for proteins) (Figure 2A, B).