Abstract: Immortalized human epithelial cell sublines are provided. The novel cell lines do not undergo terminal differentiation and senescence upon exposure to high calcium concentrations. The novel cells exhibit positive reactivity with milk-fat globule membrane antigen and cytokeratin anti-serum. The cells are non-tumorigenic in athymic mice, and exhibit both three-dimensional growth in collagen and dome formation in confluent cultures. The cell sublines demonstrate growth control by hormones and growth factors. The novel cell sublines are useful in evaluating the capacity of preselected agents to bring about a change in epithelial cell growth and in the production of proteins.

Abstract: A breakaway support structure for a sign, light, or mailbox. A foundation post is anchored in the ground and has a projection extending from an upper end. A support post has a sleeve on a lower end which receives the projection. The sleeve and projection are interconnected by at least one linking member which has a preferentially breakable portion. The linking member in one embodiment may be an eyebolt which receives a shear pin. In another embodiment, the projection is a coil spring which is secured on one end to the foundation post and is connected to an annular housing on the lower end of the support post by two spaced fasteners having preferentially breakable portions. In another embodiment, a conventional sign post is retained in a cup-shaped housing that is connected to the projection of the foundation post by at least one linking member which has a preferentially breakable portion.