RASSF1 and ductal breast carcinoma in situ: Our observed increase in RASSF1A gene and protein expression, evident in these DCIS.com cells in response to increasingly stiffer environments, both in vitro (Figure 2) or in situ (Figure 3), and in association with local mammary gland stiffness in WT BRCA patient tissue (Figure 4), may be in order to maintain a differentiated epithelial phenotype (Figure 6, orange arrows and pathway).