Changing the fontsize of axis annotations in a hexbinplot

I would like to increase the font size of axis annotations in a hexbinplot.

library(hexbin)
df <- data.frame(x=rnorm(1000),y=rnorm(1000))
hb <- hexbin(x=df$x, df$y)
myPlot <- plot(hb, xlab="", ylab="", legend=FALSE)

I would like the -3, ..., 2 and the -2, ..., 3 on the axes to be larger.

This earlier thread already helped me with axis labels, but the suggestion about how to change the annotations ("use grid.ls()" - how?) is a little too cryptic for me. I am more fluent in base graphics than in lattice.