Effect of factors influencing PLC activity on the Hsp70 level in A431 cells. A – A431 cells were treated with EGF, Tyrphostin AG1478 and U73122, able to affect PLC activity, and lysates of cells were taken in 15 min and in 6 h after administration of the agents. The lysates were subjected to PAGE and examined by Western blot for Hsp70 and Hsc70 as indicated using 2H9 anti-Hsp70 and N69 anti-Hsc70 antibody respectively. The amount of Hsp70 shown on the Western blot was quantified by densitometry and normalized to the total protein loaded into each lane of the gel. B – Hsp70 level is reduced in the A431 cells treated with U73122; immunofluorescence with the use of 2H9 antibody. C – U73343 is not able to decrease the Hsp70 amount in A431 cells; lysates of the cells treated with U73122 and its non-active analog U73343 were analyzed by Western blot, using 2H9 antibody.