Activated Cdc42-associated kinase (ACK) has been shown to be an important effector molecule for the small GTPase Cdc42. We have shown previously an essential role for Cdc42 in the transduction of Ras signals for the transformation of mammalian cells. In this report, we show that the ACK-1 isoform of ACK plays a critical role in transducing Ras-Cdc42 signals in the NIH 3T3 cells. Overexpression ...

Acetate kinase (ACK) catalyzes the reversible synthesis of acetyl phosphate by transfer of the γ-phosphate of ATP to acetate. Here we report the first biochemical and kinetic characterization of a eukaryotic ACK, that from the protist Entamoeba histolytica. Our characterization revealed that this protist ACK is the only known member of the ASKHA structural superfamily, which includes acetate ki...

Cdc42 is a Rho-family small G protein that has been widely studied for its role in controlling the actin cytoskeleton and plays a part in several potentially oncogenic signaling networks. Similar to most other small G proteins, Cdc42 binds to many downstream effector proteins to elicit its cellular effects. These effector proteins all engage the same face of Cdc42, the conformation of which is ...

Activated Cdc42 kinases (Acks) are evolutionarily conserved non-receptor tyrosine kinases. Activating somatic mutations and increased ACK1 protein levels have been found in many types of human cancers and correlate with a poor prognosis. ACK1 is activated by epidermal growth factor (EGF) receptor signaling and functions to regulate EGF receptor turnover. ACK1 has additionally been found to prop...

One of the challenges in reliable multicast is approximating or replicating TCP’s congestion control algorithm. This has led to various proposals to adapt TCP itself for use over multicast. The drawback of these multicast TCP services is that they place significant processing load on the sender and they fail to deal with the problem of ACK implosion. This paper shows how concast, a network-laye...

Wireless data services are fundamental in ubiquitous networks. In wireless data networks, the TCP congestion mechanism can mistake a wireless channel error or blackout for congestion on the route. Several wireless TCP protocols have been proposed considering TCP performance degradation in wireless systems. However, these protocols are too complex to deploy in wireless systems. In this paper, we...

This paper analyzes the impact of the No Ack policy in VoIP ad-hoc single-hop IEEE 802.11e networks. The No Ack policy consists on suppressing the MAC layer acknowledgement packets. This option dramatically reduces the duration of MAC frames and thus increments the maximum number of VoIP flows that can coexist in the network. The negative side is an increased packet loss rate and the consequent...

The demand for the IEEE 802.11 wireless local-area networks (WLANs) has been drastically increasing along with many emerging applications and services over WLAN. However, the IEEE 802.11 medium access control (MAC) is known to be limited in terms of its throughput performance due to the high MAC overhead, such as interframe spaces (IFS) or per-frame based acknowledgement (ACK) frame transmissio...

Many reliable multicast protocols use socalled ACK-trees to avoid the well-known acknowledgment implosion problem in case of large multicast groups. For constructing ACK trees, usually expanding ring search techniques are applied. Our simulation results show that those techniques have scalability problems itself. In this paper, we propose a novel approach for building ACK trees, the token repos...

The present work deals with the preparation and characterization of activated carbons from bark asparagus palm (Laccosperma robustum) by chemical activation phosphoric acid potassium hydroxide. process was optimized on basis analysis iodine number, methylene blue number yield as a function parameters (concentration activating agents pyrolysis temperature). It emerges that temperature concentrat...