Given that PTBP1 may regulate cortactin exon 11 which can be seen in RT-PCR (Figure 4C), we performed RNA immunoprecipitation and showed that PTBP1 efficiently coprecipitated cortactin RNA in the colorectal cancer cell line HCT-116, confirming a direct interaction (Figure 5A). The gene discussed is CTTN; the disease is colorectal cancer.