The present invention provides a linear multimeric biomolecule polymer wherein a biomolecule is bonded to a polyubiquitin scaffold formed of two or more covalently bonded ubiquitins, by obtaining, from a host cell, a biomolecule bonded with a ubiquitin C-terminal tag through recombinant expression, and polyubiquitinating the biomolecule in vitro in the presence of proteins involved in ubiquitination, E1 (activation enzyme), E2 (conjugation enzyme), and E3 (ligase), and a substrate. The polymer according to the present invention may be used in the separation and purification of a biomolecule, the separation of a target material that binds to the biomolecule, etc.

The present disclosure provides an isolated invasive cancer stem cell (iCSC) or a substantially homogeneous iCSC population comprising said iCSC, which is positive for the marker AMFR on the cell membrane. The present disclosure also provides a method of detecting the iCSC within an established cancer or a collection of cancer cells. The present disclosure also provides a method of isolating the iCSC or a substantially homogeneous cell population comprising said iCSC from an established cancer or a collection of cancer cells.