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The Ras-binding domain (RBD) of human Raf-1 was purified from Escherichia coli, and its interaction with Ras was investigated. Its dissociation constant with p21ras.guanyl-5'-yl imidodiphosphate was found to be 18 nM, with a slight preference for H-ras over K- and N-ras. Oncogenic forms bind with slightly lower affinity. The affinity of RBD for effector region mutants or the GDP-bound form of p21ras is in the micromolar range, which means that 100-fold lower affinity is not sufficient for signal transduction. The rate of the GTPase of p21ras is not modified by RBD. Since P(i) release is found not to be rate limiting, the Ras-Raf signal of the cell may be terminated by the intrinsic GTPase of p21ras.

This study sets out to test the assumption that concepts of leadership differ as a function of cultural differences in Europe and to identify dimensions which describe differences in leadership concepts across European countries. Middle‐level managers (N = 6052) from 22 European countries rated 112 questionnaire items containing descriptions of leadership traits and behaviours. For each attribute respondents rated how well it fits their concept of an outstanding business leader. The findings support the assumption that leadership concepts are culturally endorsed. Specifically, clusters of European countries which share similar cultural values according to prior cross‐cultural research (Ronen & Shenkar, 1985), also share similar leadership concepts. The leadership prototypicality dimensions found are highly correlated with cultural dimensions reported in a comprehensive cross‐cultural study of contemporary Europe (Smith, Dugan, & Trompenaars, 1996). The ordering of countries on the leadership dimensions is considered a useful tool with which to model differences between leadership concepts of different cultural origin in Europe. Practical implications for cross‐cultural management, both in European and non‐European settings, are discussed.

The ras p21 GTPase-activating protein (GAP) was purified from human placental tissue. Internal amino acid sequence was obtained from this 120,000-dalton protein and, by means of this sequence, two types of complementary DNA clones were isolated and characterized. One type encoded GAP with a predicted molecular mass of 116,000 daltons and 96% identity with bovine GAP. The messenger RNA of this GAP was detected in human lung, brain, liver, leukocytes, and placenta. The second type appeared to be generated by a differential splicing mechanism and encoded a novel form of GAP with a predicted molecular mass of 100,400 daltons. This protein lacks the hydrophobic amino terminus characteristic of the larger species, but retains GAP activity. The messenger RNA of this type was abundantly expressed in placenta and in several human cell lines, but not in adult tissues.

These data provide evidence of NF1 may function as a tumor-suppressor allele in malignant myeloid diseases in children with NF-1 and that neurofibromin is a regulator of ras in early myelopoiesis.

A cDNA encoding a receptor antagonist of interleukin 1 (IL-ira), secreted from human monocytes, has recently been isolated and sequenced

cross-cultural leadership, ethical leadership, ethics, leadership, unethical leadership,