利落，短瘦，硬棒，两眼明得像霜夜的大星

个子大，一脸横肉，努着对大黑眼珠，看着四围

大刀靠了身，眼珠努出多高，脸上绷紧，胸脯子鼓出，像两块老桦木根子

脑门亮，眼睛亮——眼眶虽深，眼珠可黑得像两口小井，深深的闪着黑光

本年利润

利润分配

管理费用

所得税费用

盈余公积

半年

一年

二年

二年半

五年

三年。

两年。

五年。

四年。

六年。

半年

一年

二年

二年半

三年

Most mitogens are secreted signal proteins that bind to cell-surface receptors. When activated by mitogen binding, these receptors initiate various intracellular signaling pathways that stimulate cell division.

These signaling pathways act mainly by releasing the molecular brakes that block the transition from the G1 phase of the cell cycle into S phase.

Most mitogens have been identified and characterized by their effects on cells in culture. One of the first mitogens identified in this way was platelet-derived growth factor, or PDGF, the effects of which are typical of many others discovered since. When blood clots form (in a wound, for example), blood platelets incorporated in the clots are stimulated to release PDGF.

PDGF then binds to receptor tyrosine kinases in surviving cells at the wound site, stimulating these cells to proliferate and help heal the wound. In a similar way, if part of the liver is lost through surgery or acute injury, a mitogen called hepatocyte growth factor helps stimulate the surviving liver cells to proliferate.