Subject mask cells

The inhibitor p27 is regulated at the post-translational level. p27 4 exists in an inactive, masked form in proliferating cells. It may be converted into the active form by an as yet unknown mechanism so that the cell cycle can be halted. Activation of p27 may be triggered by treatment of cells with TGPp, by cell-cell contact and by an increase in the cAMP concentration. Purthermore, p27 is subject to specific, ubiquitin-mediated proteolysis (see below). 

Computation of cellular spectra from individual pixel spectra for each cell identified in the binary mask. The spectra within occupied areas in the binary mask were co-addedto create a cellular spectrum. This co-addition is subject to a number of criteria aimed at eliminating weak and noisy spectra from the edge of a cell, which may also be the most contaminated by residual scattering effects. 

Further evidence that production of masked mRNA s represents the primary event in determination is supplied by dactinomycin-experi-ments with isolated induction-systems for mammalian pancreas (Rutter et al., 1964 Wessells, 1964 Wessells and Wilt, 1965), kidney tubules (Jainchill et al., 1964), heart and thigh muscle cells (Yaffe and Feldman, 1964), and chick axial system (Hein and Pierro, 1963). These systems which are being so well explored in many ways (cf. Grobstein, 1964) are very favorable subjects for such analysis. Again,... 

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