Thus, increased expression of several classical SR proteins has been observed, in correlation with cancer progression in several human tumors, including ovary, lung, colon, kidney, liver, pancreas and breast cancer; however, the mRNA levels of SRSF1, SRSF5, SRSF6 and SRSF4 are lower in non-familial colon adenocarcinomas than in healthy tissue (reviewed in [2], [5], [42]). Here, SRSF1 is linked to breast cancer.