The aim of this contribution is the application of matrix-assisted laser desorption/ionization mass spectrometric imaging (MALDI-MSI) in the area of photolithographic structuring. As proof of concept, this method was used to image an UV exposed negative photoresist layer, which is generally used to manufacture printed circuit boards (PCB) for electronic components. The negative photoresist layer consisting of the main component novolac, benzophenone as the active component, and the solvent tetrahydrofuran was mixed with the matrix dithranol and the salt additive LiTFA and spin-coated onto an ITO-conductive glass slide. To imprint an image on the created surface, a transparency with a printed wiring diagram was placed on top of it and irradiated by UV light for 15 min. The inspection of the efficient imprinting of the microstructure onto the photoresist layer was performed by MALDI-MSI. This unique application represents a further step toward the surface analysis of polymer films by this emerging life science imaging technique.

Here two murine salivary gland cancer (SGC) cell lines WR21 and SCA-9 were studied for the first time in detail by high-resolution molecular cytogenetic approaches. This study revealed that these cell lines are models for human SGCs of initial stage myoepithelioid or mucoepidermoid (WR21) and of advanced stage mucoepidermoid (SCA-9) tumors. Besides, three genes most likely playing a role in SGC development (FGF10, ELAVL1/HUR and SEL1) were identified. All of them were involved in translocation events in these in vitro models and thus were most likely activated. Overall, the present study highlights the necessity not only to establish but also to genetically characterize murine tumor cell lines. Without such a characterization they cannot be used in a reasonable way in research.