Final answer:
The false statement about lamellipodia is that they contain bundles of microtubules pushing the plasma membrane forward, when in fact, it is actin filaments that serve this function in cell motility.
Step-by-step explanation:
The statement that is false about lamellipodia is that they contain bundles of microtubules that push the plasma membrane forward. This function is incorrect because it is the actin filaments, not the microtubules, that play a critical role in pushing the plasma membrane forward. Lamellipodia formation is indeed stimulated by the activation of Rac, a small Rho GTPase that regulates cell migration and actin organization. Lamellipodia can have associated filopodia, which are thin protrusions that extend from the main lamellipodium structure. These lamellipodia are present at the leading edge of crawling cells, where they contain branched networks of actin filaments that polymerize to drive the cell forward, as per the description of their typical structure being a dendritic network pushing against the plasma membrane.
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