INSR and cancer: The presence of the A and B isoforms of the InsR was assessed and RT–PCR studies showed the existence of 600 and 636 bp fragments, representing Ins-A (Ex11−) and Ins-B (Ex11+), respectively, and also indicated that in comparison with the A549, DU145 and MCF-7 cancer cells, LoVo cells consistently expressed elevated amounts of InsR-A mRNA, with minimal detection of InsR-B mRNA (Figure 2C).